Split lock washers apply greater bolt tension per unit of applied torque to help prevent rotation and loosening. Heavy-duty load-bearing construction helps increase elastic properties of the joint to compensate for material expansion and contraction maintain tension under dynamic loads.Specification: Item : Split Lock WasherType : Heavy DutyMaterial : SteelFinish : ZincFits Bolt Sizes : 5/16"Size : 5/16"Inside Dia. : 0.314"Outside Dia. : 0.593"Thickness : 0.097"Meets/Exceeds : ASME B18.211Package Quantity : 100"