... .Most competitive price. 4.ROHS approved. Details about o ring color code: Materials Comply with ROHS, NBR, Silicone (VMQ), EPDM, Viton, etc ... request.Tolerance Strictly upon international standard, no flash.Color Black, transparent, green, red, yellow, grey, purple, pink or as your requested.Quantity ... , Metric and BS o rings are all available. o ring color code