SEMS bolt is a pre-assembled fastener with one or more free-spinning washers retained on the shank. The washer is trapped by the rolled thread so it cannot fall off, while still rotating freely during installation. It eliminates manual washer assembly, saves labor and prevents missing washers. Available with plain washer, spring lock washer or serrated lock washer. Material: carbon steel, stainless steel; finishes: zinc plated, black oxide. Widely used in electronics cabinets, electrical equipment and machinery assembly.