... .AS568A3. GB/T3452.11)Rubber O-RING NBR o-ring, EPDM o-ring,viton o-ring, Siliconeo-ring,FKM o-ringRubber Seal ring,seal circle ... 3. GB /T3452.11)Rubber O-RING NBR o-ring, EPDM o-ring,viton o-ring, Silicone o-ring,FKM o-ringRubber Seal ring,seal circle ... : black, blue, brown, green, red, white, purpleROHS approvedHardness:60-90 shore Contact me!!!