... back ring rubber seat with resin back ringvalve seat Features:1:EPDM is copolymerized by ethylene and propyleneso, so heat resistance ... :-50oC~150 oC6:Specification rangings from 1.5 "to 16 ", if exceed 16 ", it must be aluminum back.7:We have got the ... ,CR,SI,FPM,PTFE etc.Back Ring Material: Phenolic mouldingpowder, Aluminum and FRP etc.Order Notes:This is fit for reference ...