For bolting a neck onto a contoured solidbody when a flat neck attachment plate is impractical. 5/8"-diameter counterbore holes required. Supplied in packages of 12.
Use a 5/8" diameter Counterbore, Forstner, or brad-point drill bit to recess these neck bolt washers to 3/16" standard depth (this may vary according to instrument design). The center hole is 3/16"-diameter.