#12 Neoprene EPDM Bonded Sealing Washers Stainless Steel 18-8, Neo Bond, 100 Pieces (#12 Neobond Washer 18-8) Works with #12 Sized Screws Stainless Steel 18-8 for high corrosion resistance Used to prevent leakage, distribute pressure of the bolt or screw. Neoprene EPDM Bonded Sealing Washer 1/2 Inch Outer Diameter