O-ring in NBR,HNBR,EPDM,Silicone,Viton,etc Hardness:ShoreA60,7,80,90 Color:black,green,yellow ... ,blue,etc NSF,WRAS,TZW,W270,FDA ItemNBR O-ring ... automobiles.Shore 60±5 ; 70±5AdvantageGood Ozone resistance, aging resistance, high/low temperature resistance, acid/alkali resistance, weather resistance, abrasion resistance ...