... ,NSF 4.OEM/ODM customized EPDM sealing ring Good factory for rubber seal ring features:1. Materials advice: silicone and rubber (EPDM, also NBR ... , SI, HNBR, SBR, CR, BR, IIR, NR, etc),as your request , Environmental Friendly.2. Application ... inside, strength carton outside, or as your request. customized EPDM sealing ring