3.5MM CS X 21MM ID BLACK BUNA 70D

H3.5X21 is a black Buna-N (Nitrile) 70 Shore A O-Ring supplied with an inside diameter of 21 mm (0.827 in), a cross section of 3.5 mm (0.138 in), and an outside diameter of 28 mm (1.1 in). In service, this o-ring creates a positive seal at flange, piston and rod interfaces without added hardware.

As a material, Buna-N (Nitrile) is valued for reliable performance in both static and dynamic service, low compression set under sustained load. The material holds up against greases and lubricants, petroleum-based oils, and many alcohols. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). It is not the right choice where ozone and direct sunlight or polar solvents are present.

Maintenance and OEM teams specify it across hydraulic and pneumatic systems, agricultural equipment, and automotive.

H3.5X21 ships individually. Unit weight is approximately 0.98 g. As always, verify media compatibility and operating conditions against the requirements of your specific application. For a size or compound outside the standard catalog, APG can quote from a print or sample.