Description Warranty Information (Priced at 10 per box) Teco Heavy Duty Hardened Flat Washers 42621 Black Oxide Finish Case Hardened C1010 Material Material C1010 Steel Finish Black Oxide Type Flat Washer Stud Size 3/8 Inside Diameter (A) 0.406 in Outside Diameter (B) 0.875 in Thickness (C) 0.188 in Te-Co Heavy Duty Flat Washers