Fastener Seal - Zinc-Plated Steel with Buna-N Rubber Sealing Washer Type Metal Bonded Washer Finish Zinc Plated Metal Material Steel Material Grade/Class Not Graded For Screw Size 3/4 in Inside Diameter 0.765 in Outside Diameter 1.375 in Maximum Thickness 0.18 in Seal Material Buna-N System of Measurement Inch Pack Size Small Pack