Bonded Tek Screw Sealing Roofing Washers Epdm Rubber Waterproof Ø 16mm 19mm 29mm

The other side is neoprene EPDM, which has the properties of ageing resistance, resistance to high and low temperatures, acid and alkali resistance. - Material : 304 stainless steel/carbon steel galvanised/aluminium + EPDM rubber.

eBay