Product Information Seal: Buna-N Select a Product Part NumberMaterialAdapter SizeCoupler Size ADA2030EZ356T6 Aluminum3"2" ADA4030EZ356T6 Aluminum3"4" ADA4020EZ356T6 Aluminum2"4" ADA3020EZ356T6 Aluminum2"3" ADA6040EZ356T6 Aluminum4"6" ADA3040EZ356T6 Aluminum4"3" RDA3020EZ316 Stainless Steel2"3" RDA6040EZ316 Stainless Steel4"6" RDA2010EZ316 Stainless Steel1"2" RDA2030EZ316 Stainless Steel3"2" RDA4030EZ316 Stainless Steel3"4" RDA4020EZ316 Stainless Steel2"4" RDA3040EZ316 Stainless Steel4"3"