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 Resistant Vibration Resistant Rockwell Hardness HRC40 System of Measurement Inch Package Quantity 200