5/16” washers have a maximum outside diameter of 0.95 and maximum inside diameter of 0.39. These USS washers are similar to SAE washers but note they will have a slightly greater outer and inner diameter. Mount washers around a bolt or screw between the fastener’s bearing surface and the object or portion it’s connected to. Distributes stress and spans wider holes. Bulk package of stainless steel washers weighs approximately 50 lbs. For more sign bolt post parts, galvanized posts, and aluminum signs, trust 95TSS.