Lock Washer, Lock Washer Type Wedge Lock, Finish Delta Protect, Material Steel, For Screw Size 5/16 in, Inside Diameter 0.326 in, Outside Diameter 0.628 in, Maximum Thickness 0.142 in, Assembly Thickness 0.142 in, Color Silver, Material Grade/Class Case Hardened, Pack Size Small Pack, Resistance Properties Shock , Vibration , Rockwell Hardness HRC40, System of Measurement Inch, Package Quantity 200