Low carbon split lock washers are used under bolt heads or nuts to increase the hold of the fastener or to increase the bearing surface. Split lock washers are helical-shaped split rings. When fastened, the two ends exert a spring force on the fastener to create increased friction and resistance to motion. Dimensional specifications are governed by ASME B18.21.1. Available in zinc plated finish. Zinc plating sacrifices itself, corroding before the base material, offering added corrosion resistance.