Billet Aluminum Plain Socket Cap Washer Machined to the same dimensions as our Lightning washers, these plain billet aluminum socket cap washers have a smooth outer edge. They are recessed to accept a socket cap screw. Available in a raw machined or bright polished finish as well as a variety of anodize and Fusioncoat colors. Sold individually. Bolt not included, washer only Size Selection: #10 Size is recessed to accept a socket cap screw (sold separately), the billet washers have a 5/8" outside diameter 1/4" Size is recessed to accept a 1/4" socket cap screw (sold separately) the billet washers have a 3/4" outside diameter. 5/16" Size is recessed to accept a 5/16" socket cap screw (sold separately) the billet washers have a 1" outside diameter. 3/8" Size is recessed to accept a 3/8" socket cap screw (sold separately) the billet washers have a 1 1/8" outside diameter