O-rings are closed circular rings of circular cross-section. They are made through vulcanization from form tools as a complete ring. The sealing function of the O-ring is achieved by the deformation of the cross-section when installed and compressed in its housing. The O-ring can be compressed either radially or axially in its installation housing. In operating conditions the pressure exerted by the media reinforces the sealing function, as under pressure the elastomer material functions as a non-compressible fluid. DICHTOMATIK O-Ring, 1.234 in Inside Dia, 1.512 in Outside Dia, Cross Section: 0.139 in, Circular Torus Cross Section, Dash Number: 218, 70 Shore A Durometer, 40 to 120 °F, Nitrile Rubber, Black, Import