There are variouse type of"o ' Rings available from 1mm cross section to 10mm. and inner diameter0.5 to1000mm. in a diffarent polymers like Nitrile / Neoprene/EPDM/Silicone/ Viton/Polyacrylic etc.
used in Automobile indusries,industrial/engineering industries, Macanical seal manufacturing indusrties
etc.