“Air Ventilator Black”

$146.50$550.50
Some Sizes Out of Stock Temperature Range: -20°F to +180°F Sizes I.D. (in.): 4, 6, 8, 10, 12, 14, 16, 18, 20, & 24

“Air Ventilator Heavy-Duty”

$183.50$597.50
Temperature Range: -20°F to +180°F Sizes I.D. (in.): 6, 8, 12, 14, 16, & 24

“Air Ventilator Yellow”

$146.50$550.50
Temperature Range: -20°F to +180°F Sizes I.D. (in.): 4, 6, 8, 10, 12, 14, 16, 18, 20, & 24

“Air Ventilator White”

$146.50$550.50
Temperature Range: -20°F to +180°F Sizes I.D. (in.): 4, 6, 8, 10, 12, 14, 16, 18, 20, & 24

“Air Ventilator Insulated”

$542.00$918.00
Some Sizes Out of Stock Temperature Range: -20°F to +180°F Sizes I.D. (in.): 8, 12, 14, & 16

“Spiral-Lock (Teflon) 600”

$552.00$3,523.50
Lead Time 4-6 Weeks Temperature Range: -65°F to +600°F Sizes I.D. (in.): 4, 6, 8, 10, & 12

“Spiral-Lock (Silicone 2P) 750”

$599.80$5,992.50
Lead Time 4-6 Weeks Temperature Range: -65°F to +750°F Sizes I.D. (in.): 4, 5, 6, 8, 10, & 12

“Neoprene Flex Conductive”

$441.75$2,542.25
Lead Time 4-6 Weeks Temperature Range: -40°F to +250°F Sizes I.D. (in.): 1, 1.25, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 10, 12, 14, 16, & 18

“Spiral-Lock (Silicone 1P) 550”

$314.80$2,729.50
Lead Time 4-6 Weeks Temperature Range: -65°F to +550°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, & 18

“Spiral-Lock (Neoprene) 300”

$230.25$1,002.00
Lead Time 4-6 Weeks Temperature Range: -65°F to +250°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, & 18

“Spiral-Lock (Hypalon) 275”

$445.00$2,194.75
Lead Time 4-6 Weeks Temperature Range: -40°F to +275°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 9, 10, & 12

“Spiral-Lock (Fiberglass) 1200”

$3,078.50$9,915.75
Lead Time 4-6 Weeks Temperature Range: -40°F to 1200°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 9, 10, & 12

“Spiral-Lock (Aramid) 570”

$970.50$2,810.75
Lead Time 4-6 Weeks Temperature Range: -40°F to 570°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 9, 10, & 12

“Spiral-Lock (Alum FG) 1050”

$973.40$8,015.50
Lead Time 4-6 Weeks Temperature Range: -65°F to 1050°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 9, 10, & 12

“Wind Handler WS”

$378.25$12,843.88
Lead Time 4-6 Weeks Temperature Range: -65°F to +250°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 24, 28, 30, 36, 40, 42, 48, & 52

“Wind Handler Insulated TU”

$628.40$10,584.06
Lead Time 4-6 Weeks Temperature Range: -40°F to +250°F Sizes I.D. (in.): 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 28, 30, 36, & 40

“Wind Handler”

$324.25$2,855.00
Lead Time 4-6 Weeks Temperature Range: -65°F to +250°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, & 24

“Tornado Flex Insulated AD”

$616.00$7,086.06
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 24, 28, 30, 36, & 48

“Tornado Flex In Sack”

$448.17$1,501.93
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 6, 8, 10, 12, 14, 16, 18, 20, & 24

“Tornado Flex”

$292.25$8,058.88
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 24, 28, 30, 36, 40, 42, & 48

“Poly Fabric Flex Bridge”

$1,023.75$2,047.50
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 12, 16, 18, 20, 22, & 24

“Neoprene Flex – 2 ply WS”

$320.40$2,607.50
Lead Time 4-6 Weeks Temperature Range: -40°F to +250°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 10, & 12

“Neoprene Flex – 2 ply Heavy-Duty”

$386.00$3,662.50
Lead Time 4-6 Weeks Temperature Range: -40°F to +250°F Sizes I.D. (in.): 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, & 24

“Neoprene Flex – 2 ply”

$256.20$12,813.63
Lead Time 4-6 Weeks Temperature Range: -40°F to +250°F Sizes I.D. (in.): 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 36, 40, 42, & 48

“Acrylic Flex 325 Pharma”

$412.50$2,788.00
Lead Time 4-6 Weeks Temperature Range: -20°F to +325°F Sizes I.D. (in.): 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 7, 8, 10, & 12

“Acrylic Flex 325 Air Handler”

$208.30$1,688.00
Lead Time 4-6 Weeks Temperature Range: -20°F to +325°F Sizes I.D. (in.): 8, 10, 12, 14, 16, 18, 20, & 24

“Acrylic Flex 325”

$311.75$1,321.75
Lead Time 4-6 Weeks Temperature Range: -20°F to +325°F Sizes I.D. (in.): 2, 2.5, 3, 4, 5, 6, 7, 8, 9, & 10

“Poly Fabric Flex – 2 ply”

$310.25$911.00
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 10, & 12

“Poly Fabric Flex – 1 ply”

$273.25$712.50
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 10, & 12

“Neoprene Flex – 1 ply”

$288.25$1,668.00
Lead Time 4-6 Weeks Temperature Range: -65°F to +250°F Sizes I.D. (in.): 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, & 12

Aluminum Connectors

$21.15$69.99
Sizes I.D. (in.): 1.5, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, & 24

Stainless Steel Connectors

$30.27$50.59
Sizes I.D. (in.): 2, 3, 4, 5, 6, 7, 8, 10, & 12

Screw Clamps

$9.20$435.97
Sizes I.D. (in.): 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 14, 16, 18, & 20

Bridge Clamps

$8.29$21.19
Sizes I.D. (in.): 2, 2.25, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, & 12

J-Lock Connectors

$46.20$70.91
Sizes I.D. (in.): 4, 5, 6, 8, 10, 12, 14, 16, 18, & 20

What Are Coated Fabric Ducts?

A coated fabric duct is a type of ductwork made from a lightweight polyester fabric dipped in plastic or rubber materials such as PVC or  Neoprene. Coated poly fabric hoses are designed to serve as a lightweight alternative to rigid heavy ductwork to ventilate various commercial and industrial environments without permanently installing a complex series of metal hoses. Due to the nature of the polyester fabric, poly fabric hoses can be made in different colors, sizes, and lengths. In fact, most coated fabric hoses are created from recyclable materials, and depending on the choice of product, these flexible hoses can feature several unique designs and functions, such as flame retardancy, static dissipation, insulation, and FDA-approved ventilation and extraction. They should not be confused with regular fabric hoses because they are significantly weaker and more susceptible to punctures, scratches, and tears than their coated counterparts. With that in mind, fabric ducting has come a long way since its initial application in China in the 1950s, when they were widely used as easily installable air ducts in the refrigeration industry. While these flexible fabric hoses are strictly limited to various air ventilation applications, adding a special plastic or rubber coating can turn a flimsy flexible hose into one of the most reliable and durable flexible hoses on the market.

“Air Ventilator Heavy Duty”

Air Ventilator Heavy Duty Ventilation Hose

“Air Ventilator Yellow”

    • Lightweight duct hose.
    • Highly compressible

The “Air Ventilator Yellow” flexible ducting hose can be useful in many industrial air movement applications. These lightweight hoses are made from PVC vinyl coated polyester fabric and has been reinforced with a spring steel wire helix for added strength when flexed. Each section of yellow flex duct is constructed with a protective external wear-strip. The protective wear-strip provides an added layer of protection from dragging and scraping the hose material on the ground. All hose ends feature belted cuffed end for easy installation. This allows for quick and simple use without the need for clamps.

This PVC flexible ducting hose is lightweight and cost effective. The Air Ventilator hoses are our least expensive hose products and are priced at a fraction of most hoses in their class. All hose material in the “Air Ventilator Yellow” flex duct has a temperature range of-20 to +180 degrees Fahrenheit for industrial air movement. Each section of the hose material is highly compressible and standard lengths are 25 feet. The flex duct can easily retract so it can be compressed from its full length down to just three feet. This makes transportation and storage convenient, especially when the hose is used for seasonal applications. These lightweight hoses are available in several different sizes, including 4, 6, 8, 10, 12, 16, 18, 20, and 24 inch. This flex duct is generally inventoried in the aforementioned sizes and will ship within 24 hours of an order. In addition, all sizes of the “Air Ventilator Yellow” can ship via FedEx Ground, making for a less expensive fulfillment option.

What Is the Difference Between PVC (Vinyl) and Neoprene Coated Fabric Ducts?

PVC vinyl-coated ducts and neoprene-coated fabric ducts are some of the most widely used coatings for fabric flex hoses due to their overall strength, durability, and resilience to a wide variety of elements. One of the most significant benefits of PVC-coated fabric ducting is its ability to withstand environmental conditions and general wear and tear, making it one of the most versatile lightweight ducting options for general all-purpose ventilation. However, when directly compared to a neoprene-coated fabric hose, PVC-coated hoses showcase less strength and resilience. Due to Neoprene’s chemical composition, these coated hoses showcase a more robust tensile strength and resilience towards industrial-grade abrasion, chemicals, and oils. This makes them especially ideal for abrasive material handling applications that require a certain threshold of strength and resilience that doesn’t break the bank in the process. Neoprene coated fabric hoses are used to move abrasives and materials as well air. Depending on the product choice, it is essential to note that both neoprene and PVC-coated ducts can feature a compressible and retractable design, making them ideal for applications that require these hoses to be moved and stored frequently. While a neoprene-coated fabric hose is a more durable option, PVC vinyl-coated flex hoses are more widely available and accessible in different colors, sizes, product types, and customization options. One last note is that generally, PVC coated fabric hoses are less expensive than their neoprene counterparts. This makes them ideal for applications that require temporary ducting or installations that see excessive abuse from exterior elements.  Determining which is the better ductwork option will heavily depend on the application, environment, and machine requirements.

“Neoprene Flex Conductive”

2 black neoprene hoses half shown length downwards
Neoprene Flex Conductive Flex Black in Color Flex laid out

“Air Ventilator White”

Air ventilator White

“Poly Fabric Flex Bridge”

Black and white two polyfabric flex bridge upclose shot pointing left
Black and white polyfabric flex bridge upclose shot pointing up

What Is PVC Coated Ductwork?

A PVC (Polyvinyl chloride) coating is a specific design choice to make a fabric flexible hose more resilient against general wear and tear for ventilation applications. It is one of the most common types of coatings on the market due to PVC’s availability, accessibility, and longevity. These coated flex ducts are available in various inside diameter (I.D.) sizes, lengths, and colors, giving operators a range of options to choose from so they can find the appropriate flex duct for their application. While the overall durability and service life of a PVC-coated flexible hose will depend on how thick the coating is, a PVC coating is generally strong and versatile enough to withstand various weather conditions and chemicals. For instance, a PVC-coated fabric hose such as our “Air Ventilator” series can withstand environments with temperatures ranging from -20 to +180 degrees Fahrenheit, which makes them great for extreme temperature ventilation applications such as smoke ducting, utility blowing, and dehumidification. While this type of flexible ducting is mainly geared toward air and fume ventilation, a PVC-coated fabric duct can last for years at a time, making it one of the most cost-effective coatings that will stand the test of time.

“Poly Fabric Flex – 2 Ply”

    • Wearstrip offer additional external abrasion & drag resistance
    • Great moisture, mildew, & chemical resistance
    • Available in a heavy duty bridge construction
    • Additional coatings available for better abrasion &/or chemical resistance

The “Poly Fabric Flex – 2 ply” is a double-ply PVC vinyl coated polyester fabric industrial hose reinforced with a spring steel wire helix & external PVC wear strip. This hose provides efficient air-flow and is recommended for dust control applications. This double-ply commercial duct offers more abrasion resistance, a longer product life, and less down time for material transfer applications. This industrial hose can also be ordered with additional coatings that will provide even more abrasion resistance. The construction of the hose material on this commercial duct also provides great chemical and moisture resistance while the reinforced spring steel wire helix and external PVC wear-strip offers great external abrasion resistance for harsh environments.

The “Poly Fabric Flex – 2 ply” fabric ducting has a working temperature of – 20 to +180 degrees Fahrenheit. This gives users a wider range of temperature resistance in an affordable non-high temp hose! Clogs are prevented since this flexible hose has excellent flow characteristics with low friction loss because of the smooth internal structure. This industrial hose is constructed with UL 94 V-0 flame retardant hose material and is ideal for air, dust, fume, and light material movement.

“Tornado Flex In Sack”

$448.17$1,501.93
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 6, 8, 10, 12, 14, 16, 18, 20, & 24

“Tornado Flex Insulated AD”

$616.00$7,086.06
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 24, 28, 30, 36, & 48

“Tornado Flex”

$292.25$8,058.88
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 24, 28, 30, 36, 40, 42, & 48

“Tornado Flex Insulated AD”

torando flex insulated AD belt loop entry shot and funnel cuff entry shot

How Is PVC Coating Done?

PVC coating is a process that gives a poly fabric flexible duct strength and longevity against light abrasive materials and natural elements. The coating process is typically done through manufacturing facilities that prepare vats of liquid plastic for these flexible ducts to be dipped and coated. There are two main types of dipping procedures: a Hot Dip and a Cold Dip. The Hot Dip is the most common technique that requires the vat of liquid plastic to be heated up, and the fabric is to be dipped for several seconds and extracted, giving the product a protective coating layer of PVC. It is important to note that the thickness of the PVC coating is going to be largely dependent on how high the liquid plastic is heated up. For the cold dip, which is less commonly used, manufacturers dip products into a cold vat of liquid PVC multiple times to reach their desired coating thickness. This method is usually reserved for products and materials that cannot withstand preheated liquid plastic dipping, such as fabric or wood. Regarding how poly fabric flex hoses receive their PVC coating, our flexible ducts are dipped in cold PVC liquid and utilize rotational molding and drying techniques to ensure that the PVC coating properly covers every inch before it is formed into a flexible duct. It is essential to note that this coating process applies to rubber coatings such as neoprene. By having these flexible hoses dipped in liquid plastic and rubber, it ensures the durability and longevity of the flex hose during their intended application and ensures its operators that these coated hoses can cater to their intended application. Additionally, investing in a coated fabric hose is an assured investment that will significantly reduce the wear, damage, and eventual replacement of flexible hoses and optimize the output of their paired machinery.

“Tornado Flex”

    • Lightweight duct for blower applications
    • Highly compressible

The “Tornado Flex” industrial hoses are made from hose materials that are listed as UL 94V-0 flame retardant. UL 94V-0 means that these hose materials stop burning within 10 seconds of being exposed to a flame (given that the source of fuel is removed from the burn area). This product is also manufactured with materials that meet NFPA 701 standards. This flexible air ducting has a temperature range of -20 degrees to +180 degrees Fahrenheit. The lightweight nature of these industrial hoses combined with their ability to withstand high and low temperatures make them a great choice for a wide variety of applications involving airflow. The “Tornado Flex” lightweight hose is made-to-order and comes in standard 25 ft lengths. The standard color for this product is yellow with a black wear-strip, but custom colors are available upon request in olive drab, tan, blue and white. This lightweight hose comes with plain cut ends but cuffs and belted finishes are available and can be factory installed at the time of production.

The standard internal diameter sizes offered for this flexible air ducting product range from 4 to 24 inches with custom sizes available up to 52 inches. The lightweight construction of this flexible air ducting gives it a wide range of applications involving airflow such as blower hoses, wave pool blowers, mining, A/C ventilation, cold air supply, humidity control, and smoke ejectors. If you have questions or need additional information, please do not hesitate to give one of our ducting specialists a call today!

“Neoprene Flex – 1 ply”

$288.25$1,668.00
Lead Time 4-6 Weeks Temperature Range: -65°F to +250°F Sizes I.D. (in.): 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, & 12

“Neoprene Flex – 2 ply Heavy-Duty”

$386.00$3,662.50
Lead Time 4-6 Weeks Temperature Range: -40°F to +250°F Sizes I.D. (in.): 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, & 24

“Spiral-Lock (Fiberglass) 1200”

$3,078.50$9,915.75
Lead Time 4-6 Weeks Temperature Range: -40°F to 1200°F Sizes I.D. (in.): 4, 5, 6, 7, 8, 9, 10, & 12

“Spiral-Lock (Hypalon) 275”

$445.00$2,194.75
Lead Time 4-6 Weeks Temperature Range: -40°F to +275°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 9, 10, & 12

“Neoprene Flex – 2 Ply”

Neoprene Flex 2 ply Black in color wrapped around itself pointing at the screen

What are Neoprene Coated Fabric Hoses Used For?

Neoprene-coated fabric ducts are a type of poly fabric flex hose dipped in neoprene, a flexible synthetic material produced from carbon and hydrogen atoms. As a material, neoprene is generally stronger than natural rubbers and exhibits high tensile strength and resistance to chemicals, abrasion, oils, and solvents. Due to its overall strength and flexibility, the material is used in a variety of products in the medical field, automotive industry, and especially for industrial collection and ventilation. A neoprene-coated flex duct is especially effective in material handling applications, and depending on the type of abrasive material that needs to be collected, these coated hoses are readily available in different weight classes and wall thicknesses. One of the most significant advantages of utilizing neoprene-coated flex hoses is their ability to employ unique designs and passive functional features such as flame retardancy, static dissipation, and degradation resistance. These features alone make them applicable in more sectors and specialized applications such as food-grade ducting and industrial vacuuming. Furthermore, you can customize neoprene-coated flex ducts with inside diameter (I.D.) sizes that can go up to 60 inches and acquire custom lengths and end finishes to ensure they fit into your machinery. With all these features in mind, a neoprene-coated fabric hose is one of the best-suited flex ducts that can cater to industrial workshops and facilities looking for reliable and versatile ductwork that does not sacrifice flexibility with durability.

“Spiral-Lock (Neoprene) 300”

“Spiral-Lock (Neoprene) 300”1
“Spiral-Lock (Neoprene) 300”2

“Acrylic Flex 325 Air Handler”

$208.30$1,688.00
Lead Time 4-6 Weeks Temperature Range: -20°F to +325°F Sizes I.D. (in.): 8, 10, 12, 14, 16, 18, 20, & 24

“Acrylic Flex 325 Pharma”

$412.50$2,788.00
Lead Time 4-6 Weeks Temperature Range: -20°F to +325°F Sizes I.D. (in.): 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 7, 8, 10, & 12

“Acrylic Flex 325”

$311.75$1,321.75
Lead Time 4-6 Weeks Temperature Range: -20°F to +325°F Sizes I.D. (in.): 2, 2.5, 3, 4, 5, 6, 7, 8, 9, & 10

“Poly Fabric Flex – 2 ply”

$310.25$911.00
Lead Time 4-6 Weeks Temperature Range: -20°F to +180°F Sizes I.D. (in.): 3, 4, 5, 6, 7, 8, 10, & 12

What Is More Affordable Vinyl Coated Ducts or Neoprene Coated Ducts?

When it comes to determining which coated fabric ducting is the most affordable option, there is no debate that a PVC vinyl-coated fabric hose is the less expensive option out of the two. As PVC vinyl is a frequently used material for coating flexible fabric structures, these flexible ducts are produced and sold at an affordable and cost-conscious rate that can suit many applications. While a neoprene-coated fabric hose is more expensive, these flexible hoses offer industrial operators an exceptionally tensile option that can withstand the daily rigors of industrial material collection and ventilation, making them worth the higher cost. In addition, neoprene-coated fabric hoses feature products with specialized functional features such as static dissipation, which are ideal for industrial facilities that extract and collect abrasive materials that can create a static buildup. As a result, for those who are looking for a sturdy, flexible ducting option with additional passive functionality, then neoprene-coated fabric ducts are the better option out of the two. No matter which coated fabric duct you choose, you should not base your decision completely on affordability and price. If you select a flex hose that is not suited for the job, you risk damaging it during your application and rendering it inoperable. So, when you are choosing a coated poly fabric hose for your application, it is essential to select a flexible hose that is the best-suited option for your application.

“Air Ventilator Black”

  • Lightweight duct hose.
  • Highly compressible
  • Ideal duct for blower applications

“Air Ventilator Black” flexible ducting has a working temperature range from -20 to + 180 degrees Fahrenheit. Each commercial hose is sold in 25 ft lengths. With the wear-strip providing substantial abrasion resistance, the lightweight hose is perfect for blower applications. The “Air Ventilator Black” is available in internal diameter sizes of 4, 6, 8, 10, 12, 16, 18, 20 and 24 inches. Stocked in all noted sizes, this hose is able to ship within 24-hours of an order. All sizes of this flexible ducting can be shipped via FedEx small package delivery, bypassing the need for pricey LTL services.

The “Air Ventilator Black” lightweight hose is ideal for general air ventilation, mobile chillers, and light dust movement. The commercial hose can be utilized in a variety of ways such as: aerospace, air duct cleaning, A/C ventilation ducts, blower hose, chiller, cold air supply, confined space ventilation, dehumidification, fans and blowers, function tent HVAC, HEPA, humidity control, HVAC, mining, pet training hose, safety equipment, smoke ejectors, utility blowers, ventilation and wave pool blowers. Please do not hesitate to give one of our ducting specialists a call if you need any additional information or have any questions.

Short Length Hoses Interchangeable
Overstock Inventory Interchangeable