Our weld-on washers are CNC machined in-house from aircraft quality 4130 chromoly. They are 1/4″ thick and are designed to reinforce bolt holes by increasing the surface area thickness below the bolt head and nut. You can also use these to fix holes that have been damaged and ovaled out from loose hardware. These can be MIG or TIG welded onto mild steel or chromoly. They are sold in a pack of 4 washers. The 7/16″ – 9/16″ sizes have a 1.25″ OD and the larger 5/8″ – 3/4″ sizes have a 1.50″ OD.