Steel USS Washer, Zinc Yellow Fastener Finish, Fits Bolt Sizes 1 in, 2 1/2 in Washer Outside Dia./ CROSS-SECTIONAL SHAPE STYLE: 2 BLANK RECTANGULAR HOLE DIAMETER: 1.063 INCHES NOMINAL PERIPHERAL SHAPE STYLE: 1 ROUND CENTER HOLE SHAPE STYLE: 1 ROUND THICKNESS: 0.136 INCHES MINIMUM AND 0.192 INCHES MAXIMUM OVERALL DIAMETER: 2.500 INCHES NOMINAL END ITEM IDENTIFICATION: MRAP-RG33 HARDNESS RATING: 38.0 ROCKWELL R MINIMUM AND 45.0 ROCKWELL R MAXIMUM COLOR: YELLOW OVERALL MATERIAL: STEEL OVERALL SURFACE TREATMENT: ZINC OVERALL