1/2" ASTM F436 Thru-Hardened Yellow Zinc Steel Structural Flat Washer Made in USA / CROSS-SECTIONAL SHAPE STYLE: 1 RECTANGULAR HOLE DIAMETER: 0.531 INCHES NOMINAL PERIPHERAL SHAPE STYLE: 1 ROUND CENTER HOLE SHAPE STYLE: 1 ROUND THICKNESS: 0.097 INCHES MINIMUM AND 0.177 INCHES MAXIMUM OVERALL DIAMETER: 1.063 INCHES NOMINAL END ITEM IDENTIFICATION: F-15SA PART NAME ASSIGNED BY CONTROLLING AGENCY: STRUCTURAL FLAT WASHER, THRU HARDENED COLOR: YELLOW OVERALL MATERIAL: STEEL OVERALL SURFACE TREATMENT: ZINC OVERALL SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: ASTM F1941 ASSN STD SINGLE TREATMENT RESPONSE OVERALL