5/16 ID x 1-1/2 inch OD, 20 gauge 304 Stainless Steel Back with 0.065 Bonded EPDM Rubber Washer. Fits 5/16 size threaded fasteners. 1000/Box. Price/Box.
MATERIALS: 20 gauge (0.036") 304 Stainless Steel; 0.065" Black EPDM Rubber, 70 durometer hardness per ASTM D2000; Overall washer height before compression about .140"; Available compression about 0.030"; EPDM thickness about 0.065".
OPTIONS: Also availa