3.5MM CS X 56MM ID BLACK BUNA 70D

Ordered as H3.5X56, this is a black Buna-N (Nitrile) 70 Shore A O-Ring measuring an inside diameter of 56 mm (2.205 in), a cross section of 3.5 mm (0.138 in), and an outside diameter of 63 mm (2.48 in). The o-ring seats in a machined groove and forms a leak-tight barrier when compressed between two mating surfaces.

It resists many alcohols, greases and lubricants, and propane and butane. That behavior comes from the compound itself: Buna-N (Nitrile) is widely chosen for reliable performance in both static and dynamic service, low compression set under sustained load. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Applications involving strong acids or polar solvents call for a different compound.

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

H3.5X56 ships individually. Unit weight is approximately 2.196 g. Application requirements vary, so validate compatibility with your process conditions prior to installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.