4MM CS X 121MM ID BLACK BUNA 70D

APG stocks the H4X121, a black Buna-N (Nitrile) 70 Shore A O-Ring with an inside diameter of 121 mm (4.764 in), a cross section of 4 mm (0.157 in), and an outside diameter of 129 mm (5.08 in). An o-ring creates a positive seal at flange, piston and rod interfaces without added hardware.

As a material, Buna-N (Nitrile) delivers the most widely specified general-purpose sealing elastomer, strong abrasion and tear resistance. It resists propane and butane, water, and hydraulic fluids. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). Exposure to ozone and direct sunlight or automotive brake fluid will shorten service life.

Maintenance and OEM teams specify it across fluid power, hydraulic and pneumatic systems, and general industrial maintenance.

Order part number H4X121, sold individually. Unit weight is approximately 6.323 g. Application requirements vary, so validate compatibility with your process conditions prior to installation.