0.208" ID O-Rings | McMaster-Carr

For a better seal in low-pressure applications, such as hydraulic return lines and oil drain plugs, these O-rings are softer than standard Buna-N O-rings.

Oil-Resistant Hard Buna-N O-Rings

Harder than standard Buna-N O-rings, these 90A durometer O-rings are more durable and wear resistant.

Square-Profile Oil-Resistant Buna-N O-Rings

With flat edges on all four sides, these O-rings make contact with a larger surface area than round-profile O-rings. The increased contact creates a better seal in static applications, such as hose, pipe, and faucet connections.

X-Profile Oil-Resistant Buna-N O-Rings

With four points of contact for a strong seal, these X-profile O-rings are often used in dynamic applications, such as on pistons and rotating shafts. Also known as Quattro seals and X-rings, they resist rolling and twisting better than round- and square-profile O-rings.

Oil-Resistant Mil. Spec. Buna-N O-Rings

Choose these O-rings for their adherence to strict military standards for material and construction.

FDA-Compliant Oil-Resistant Buna-N O-Rings

FDA compliant for direct contact with food, these Buna-N O-rings create a strong seal in food and beverage lines.

Oil-Resistant Clean Room Buna-N O-Rings

These Buna-N O-rings are made and bagged in an ISO Class 7 (Fed. Std. 10,000) clean room.

Oil-Resistant Metal- and
X-Ray-Detectable Buna-N O-Rings

If these O-rings deteriorate, they’ll be picked up by metal- and X-ray-detection systems.

Oil- and Abrasion-Resistant Polyurethane O-Rings

More abrasion resistant than Buna-N O-rings, these also resist mineral oil and motor oil.

High-Pressure Oil- and
Abrasion-Resistant Polyurethane O-Rings

These O-rings are harder and stronger than standard polyurethane O-rings to handle high-pressure applications.

Chemical-Resistant O-Rings

Chemical-Resistant Viton® Fluoroelastomer O-Rings

These Viton® fluoroelastomer O-rings resist a wide range of chemicals, including benzene, butyl alcohol, and ethylene glycol.

Chemical-Resistant Soft Viton®
Fluoroelastomer O-Rings

Softer than standard Viton® fluoroelastomer O-rings, these offer a better seal in low-pressure applications.

Chemical-Resistant Hard Viton®
Fluoroelastomer O-Rings

These hard O-rings offer better wear resistance than standard Viton® fluoroelastomer O-rings.

Low-Outgassing Chemical-Resistant
Soft Viton® Fluoroelastomer O-Rings

Tested to meet ASTM E595, a standard used by NASA, these O-rings give off almost no volatile emissions that could damage sensitive electronics, even in a vacuum. They’re softer than standard Viton®, so they better conform to irregular surfaces.

Low-Outgassing Chemical-Resistant
Viton® Fluoroelastomer O-Rings

Tested to meet ASTM E595, a standard used by NASA, these O-rings give off almost no volatile emissions that could damage sensitive electronics, even in a vacuum.

Square-Profile Chemical-Resistant
Viton® Fluoroelastomer O-Rings

With flat edges on all four sides, these square-profile O-rings cover more surface than round-profile O-rings for a better seal in static applications, such as hose, pipe, and faucet connections.

X-Profile Chemical-Resistant
Viton® Fluoroelastomer O-Rings

Also known as Quattro Seals and X-rings, these X-profile O-rings have four points of contact for a better seal in dynamic applications than round-profile O-rings. They also require less compression to make a seal, so they offer a longer service life.

Chemical-Resistant Super-Resilient
Viton® Fluoroelastomer O-Rings

These durable O-rings bounce back to shape after repeated compression better than other types of Viton® fluoroelastomer O-rings.

Chemical-Resistant Brown
Viton® Fluoroelastomer O-Rings

Because one black O-ring looks just like another, these O-rings are brown for easy identification.

Chemical-Resistant High-Purity Clean
Room Viton® Fluoroelastomer O-Rings

These are the highest purity chemical-resistant O-rings we offer. They are made and bagged in an ISO Class 7 and Fed. Spec. Class 10,000 clean room, plus they’re USP VI certified; not for use in medical applications.

Chemical-Resistant Clean Room
Viton® Fluoroelastomer O-Rings

Made and bagged in an ISO Class 7 and Fed. Spec. Class 10,000 clean room.

Chemical-Resistant Mil. Spec.
Viton® Fluoroelastomer O-Rings

All of these O-rings meet MIL-R-83248C.

Chemical- and Steam-Resistant
Viton® Fluoroelastomer O-Rings

In addition to resisting chemicals, such as benzene, butyl alcohol, and ethylene glycol, these Viton® fluoroelastomer ETP O-rings resist steam.

Ultra-Chemical-Resistant Rigid PTFE O-Rings

Rigid and hard with a slippery surface, these PTFE O-rings resist harsh chemicals, such as acetone, fluorinated solvents, methanol, and boric acid.

Ultra-Chemical-Resistant Kalrez 4079 O-Rings

Inherently softer and more compressible than PTFE O-rings, these Kalrez 4079 O-rings have comparable chemical resistance.

Ultra-Chemical-Resistant
Super-Resilient Kalrez 7075 O-Rings

Able to bounce back after repeated compression, these Kalrez 7075 O-rings last longer than other Kalrez O-rings when exposed to repeated heating/cooling cycles.

Ultra-Chemical- and Steam-Resistant
Kalrez 6375 O-Rings

Kalrez 6375 O-rings are preferred over Kalrez 4079 for chemical-processing environments and applications involving steam.

Ultra-Chemical-Resistant
High-Purity Kalrez 6230 O-Rings

Made of Kalrez 6230, these O-rings are for use when high purity is essential, such as with food and semiconductors.

Chemical-Resistant Low-Temperature
Fluorosilicone O-Rings

These fluorosilicone O-rings remain flexible at temperatures as low as -75° F. They resist ethanol, ethylene glycol, and isopropyl alcohol.

Ultra-Chemical-Resistant Aflas O-Rings

While these Aflas O-rings are commonly used with petroleum fluids, they also resist many chemicals, such as ammonia, calcium hydroxide, and acetic, boric, and phosphoric acids.

Chemical-Resistant Metal-Detectable
Fluoroelastomer O-Rings

If these O-rings deteriorate, they can be picked up by metal detection systems.

High-Temperature O-Rings

High-Temperature Silicone O-Rings

These silicone O-rings have a round profile and are suitable for a wide range of static sealing applications.

High-Temperature Soft Silicone O-Rings

Able to withstand temperatures up to 400° F, these O-rings are softer than standard silicone O-rings for a better seal in low-pressure applications.

Square-Profile High-Temperature Silicone O-Rings

These square-profile O-rings have flat edges on all four sides, so they cover more surface than round-profile O-rings for a better seal in static applications, such as hose, pipe, and faucet connections.

High-Temperature Clean Room Silicone O-Rings

Made and bagged in an ISO Class 7 (Fed. Std. Class 10,000) clean room, these are the highest purity high-temperature O-rings we offer.

Water- and Steam-Resistant O-Rings

Water- and Steam-Resistant EPDM O-Rings

These O-rings also resist ethanol and ethylene glycol.

Water- and Steam-Resistant
High-Temperature EPDM O-Rings

These O-rings withstand higher temperatures than standard EPDM O-rings.

Water- and Weather-Resistant Neoprene O-Rings

Resistant to changing weather—from rainwater to sunlight—these neoprene O-rings are good for outdoor use.

About O-Rings

Oil-Resistant O-Rings

Oil-Resistant Buna-N O-Rings

Oil-Resistant Soft Buna-N O-Rings

Oil-Resistant Hard Buna-N O-Rings

Square-Profile Oil-Resistant Buna-N O-Rings

X-Profile Oil-Resistant Buna-N O-Rings

Oil-Resistant Mil. Spec. Buna-N O-Rings

FDA-Compliant Oil-Resistant Buna-N O-Rings

Oil-Resistant Clean Room Buna-N O-Rings

Oil-Resistant Metal- andX-Ray-Detectable Buna-N O-Rings

Oil- and Abrasion-Resistant Polyurethane O-Rings

High-Pressure Oil- andAbrasion-Resistant Polyurethane O-Rings

Chemical-Resistant O-Rings

Chemical-Resistant Viton® Fluoroelastomer O-Rings

Chemical-Resistant Soft Viton®Fluoroelastomer O-Rings

Chemical-Resistant Hard Viton®Fluoroelastomer O-Rings

Low-Outgassing Chemical-ResistantSoft Viton® Fluoroelastomer O-Rings

Low-Outgassing Chemical-ResistantViton® Fluoroelastomer O-Rings

Square-Profile Chemical-ResistantViton® Fluoroelastomer O-Rings

X-Profile Chemical-ResistantViton® Fluoroelastomer O-Rings

Chemical-Resistant Super-ResilientViton® Fluoroelastomer O-Rings

Chemical-Resistant BrownViton® Fluoroelastomer O-Rings

Chemical-Resistant High-Purity CleanRoom Viton® Fluoroelastomer O-Rings

Chemical-Resistant Clean RoomViton® Fluoroelastomer O-Rings

Chemical-Resistant Mil. Spec.Viton® Fluoroelastomer O-Rings

Chemical- and Steam-ResistantViton® Fluoroelastomer O-Rings