1.78MM CS X 39.45MM ID BLACK BUNA 70D

APG stocks the H1.78X39.45, a black Buna-N (Nitrile) 70 Shore A O-Ring measuring an inside diameter of 39.45 mm (1.553 in), a cross section of 1.78 mm (0.07 in), and an outside diameter of 43.01 mm (1.69 in). An o-ring compresses into its gland to block fluid or gas migration across a joint.

It resists hydraulic fluids, greases and lubricants, and propane and butane. That behavior comes from the compound itself: Buna-N (Nitrile) is known for the most widely specified general-purpose sealing elastomer and an economical choice for high-volume maintenance programs. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). Verify compatibility before use with ozone and direct sunlight or polar solvents.

You will find this material specified across automotive, agricultural equipment, and fluid power.

Reference part number H1.78X39.45 when ordering; the item is sold individually. Unit weight is approximately 0.39 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.