... physical and chemical properties. Description of viton O Ring:1. Materials: can be NBR, Viton, EPDM, SI, HNBR, BUNA, ... , IR, IIR, PU,E/A, ECO, CSM, FKM, FPM, etc.2. Characteristics: good physical and chemical properties.3. Hardness: 70~90A ... ~3 weeks.8. Small order quantity is welcomed. black viton o ring for valve