The Freudenberg-NOK NBR O-Ring, with a diameter of 3.984" and a 0.139" cross-section, is crafted from durable Nitrile Butadiene Rubber (NBR) with a hardness rating of 70 durometer. This O-Ring is engineered for superior sealing capabilities, particularly in applications involving oils and fuels. Its robust construction meets industry standards, ensuring reliability in various hydraulic and pneumatic systems. The O-Ring's dimensions and material composition make it a versatile choice for a wide range of industrial uses.