Boss O-Rings | McMaster-Carr

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2,202 Products

About O-Rings

Oil-Resistant Hard Buna-N O-Rings
for Straight-Thread Connections

Also known as boss O-rings, these O-rings are sized to fit straight threaded fittings to prevent leaks. With a 90A durometer hardness, they’re more wear resistant than standard Buna-N O-rings.

Oil- and Abrasion-Resistant Polyurethane O-Rings

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

Oil- and Abrasion-Resistant Polyurethane
O-Rings for Straight-Thread Connections

Commonly called Boss O-rings, these O-rings are for use in tube fittings with a straight-thread connection.

Chemical-Resistant Brown Viton®
Fluoroelastomer O-Rings for Tube
Fittings with Straight-Thread Connection

Also known as Boss O-rings, these O-rings are for use in tube fittings with a straight-thread connection. They are brown for easy identification.

Chemical-Resistant Hard Viton®
Fluoroelastomer O-Rings for Tube
Fittings with Straight-Thread Connection

Also known as Boss O-rings, these hard O-rings are for use in tube fittings with a straight-thread connection.

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 Mil. Spec.
Viton® Fluoroelastomer O-Rings
for Straight-Thread Connections

Also known as Boss O-rings, these O-rings are made for tube fittings with a straight-thread connection. They’re made of Viton® fluoroelastomer that meets MIL-R-83248 performance standards.

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

Made of Viton® fluoroelastomer, these O-rings meet MIL-R-83248 standards. They stay strong when used with chemicals such as benzene, butyl alcohol, and ethylene glycol.

Ultra-Chemical-Resistant Rigid PTFE
O-Rings for Straight-Thread Connections

Also known as Boss O-rings, these O-rings are used in tube fittings with a straight-thread connection. Made of PTFE, they withstand extreme temperatures and harsh chemicals such as fluorinated solvents, ethanol, and acetone.

Chemical-Resistant
Low-Temperature Fluorosilicone O-Rings for
Tube Fittings with Straight-Thread Connection

Flexible even at temperatures as low as -75° F, these fluorosilicone O-rings will keep your fittings free from leaks. They’re often used on fuel and coolant hose because fluorosilicone resists many chemicals, including ethanol and ethylene glycol.

Ultra-Chemical-Resistant DuPont Kalrez 4079
O-Rings for Straight-Thread Connections

Also known as Boss O-rings, these O-rings are made for tube fittings with a straight-thread connection. Made of Kalrez 4079, they combine the chemical resistance of PTFE with the springy softness of Viton® fluoroelastomer.

Ultra-Chemical-Resistant
DuPont Kalrez 4079 O-Rings

Made of Kalrez 4079, these O-rings combine the chemical resistance of PTFE with the springy softness of Viton® fluoroelastomer.

Ultra-Chemical-Resistant FFKM 4079
O-Rings for Straight-Thread Connections

The same chemical and heat resistance as Kalrez 4079 without the brand name. Also known as boss O-rings, these O-rings are sized to fit straight-thread fittings to prevent leaks.

Ultra-Chemical-Resistant FFKM 4079 O-Rings

Get the same chemical and heat resistance as Kalrez 4079 without the brand name. Even at 600° F, these FFKM O-rings resist a wide range of chemicals, including acetone, methyl ethyl ketone (MEK), potassium hydroxide, and most acids.

Water- and Steam-Resistant EPDM O-Rings for
Tube Fittings with Straight-Thread Connection

Also known as Boss O-rings, these O-rings are for use in tube fittings with a straight-thread connection.

Water- and Steam-Resistant EPDM O-Rings

These O-rings also resist ethanol and ethylene glycol.

Water- and Steam-Resistant Soft EPDM O-Rings

Soft and pliable, these O-rings create a better seal in low-pressure applications than standard EPDM O-rings. They resist water, steam, and glycol—you can also use them outdoors.

Water- and Weather-Resistant Neoprene
O-Rings for Straight-Thread Connections

Also known as boss O-rings, these neoprene O-rings seal straight-thread fittings in valve housings, outdoor enclosures, and saltwater applications.

Water- and Weather-Resistant Neoprene O-Rings

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

High-Temperature High-Purity Silicone
O-Rings for Straight-Thread Connections

Also known as boss O-rings, these O-rings are sized to fit straight-thread fittings to prevent leaks.

High-Temperature Silicone O-Rings

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

O-Ring Assortments

Oil-Resistant Hard Buna-N O-Ring Assortments
for Tube Fittings with Straight-Thread Connection

Also known as Boss O-rings, these hard O-rings are for use in tube fittings with a straight-thread connection.

Chemical-Resistant Hard Viton®
Fluoroelastomer O-Ring Assortments for
Tube Fittings with Straight-Thread Connection

Also known as Boss O-rings, these hard Viton® fluoroelastomer O-rings are for use in tube fittings with a straight-thread connection. They offer excellent resistance to wear.

About O-Rings

O-Rings

Oil-Resistant Hard Buna-N O-Ringsfor Straight-Thread Connections

Oil- and Abrasion-Resistant Polyurethane O-Rings

Oil- and Abrasion-Resistant PolyurethaneO-Rings for Straight-Thread Connections

Chemical-Resistant Brown Viton®Fluoroelastomer O-Rings for Tube Fittings with Straight-Thread Connection

Chemical-Resistant Hard Viton®Fluoroelastomer O-Rings for Tube Fittings with Straight-Thread Connection

Chemical-Resistant BrownViton® Fluoroelastomer O-Rings

Chemical-Resistant Mil. Spec.Viton® Fluoroelastomer O-Rings for Straight-Thread Connections

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

Ultra-Chemical-Resistant Rigid PTFEO-Rings for Straight-Thread Connections

Chemical-ResistantLow-Temperature Fluorosilicone O-Rings for Tube Fittings with Straight-Thread Connection

Ultra-Chemical-Resistant DuPont Kalrez 4079O-Rings for Straight-Thread Connections

Ultra-Chemical-ResistantDuPont Kalrez 4079 O-Rings

Ultra-Chemical-Resistant FFKM 4079O-Rings for Straight-Thread Connections

Ultra-Chemical-Resistant FFKM 4079 O-Rings

Water- and Steam-Resistant EPDM O-Rings forTube Fittings with Straight-Thread Connection

Water- and Steam-Resistant EPDM O-Rings

Water- and Steam-Resistant Soft EPDM O-Rings

Water- and Weather-Resistant NeopreneO-Rings for Straight-Thread Connections

Water- and Weather-Resistant Neoprene O-Rings

High-Temperature High-Purity SiliconeO-Rings for Straight-Thread Connections

High-Temperature Silicone O-Rings

O-Ring Assortments

Oil-Resistant Hard Buna-N O-Ring Assortmentsfor Tube Fittings with Straight-Thread Connection

Chemical-Resistant Hard Viton®Fluoroelastomer O-Ring Assortments for Tube Fittings with Straight-Thread Connection

Oil-Resistant Hard Buna-N O-Rings
for Straight-Thread Connections

Oil- and Abrasion-Resistant Polyurethane
O-Rings for Straight-Thread Connections

Chemical-Resistant Brown Viton®
Fluoroelastomer O-Rings for Tube
Fittings with Straight-Thread Connection

Chemical-Resistant Hard Viton®
Fluoroelastomer O-Rings for Tube
Fittings with Straight-Thread Connection

Chemical-Resistant Brown
Viton® Fluoroelastomer O-Rings

Chemical-Resistant Mil. Spec.
Viton® Fluoroelastomer O-Rings
for Straight-Thread Connections

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

Ultra-Chemical-Resistant Rigid PTFE
O-Rings for Straight-Thread Connections

Chemical-Resistant
Low-Temperature Fluorosilicone O-Rings for
Tube Fittings with Straight-Thread Connection

Ultra-Chemical-Resistant DuPont Kalrez 4079
O-Rings for Straight-Thread Connections

Ultra-Chemical-Resistant
DuPont Kalrez 4079 O-Rings

Ultra-Chemical-Resistant FFKM 4079
O-Rings for Straight-Thread Connections

Water- and Steam-Resistant EPDM O-Rings for
Tube Fittings with Straight-Thread Connection

Water- and Weather-Resistant Neoprene
O-Rings for Straight-Thread Connections

High-Temperature High-Purity Silicone
O-Rings for Straight-Thread Connections

Oil-Resistant Hard Buna-N O-Ring Assortments
for Tube Fittings with Straight-Thread Connection

Chemical-Resistant Hard Viton®
Fluoroelastomer O-Ring Assortments for
Tube Fittings with Straight-Thread Connection