USS Flat Washers
Flat Washers are a thin, flat, circular steel part with a centrally located hole. Washers are designed for assembly around a bolt or screw, between the bearing surface of the fastener and the part to which it is attached. Flat washers are used to improve stress distribution, and to span large clearance holes. USS washers are designed to meet the majority of industrial applications in manufacturing, maintenance, and repair. USS pattern is the most common type of flat washer. SAE pattern is a tighter fit on the bolt and a smaller outside diameter.