Split lock washers - also known as split ring washers - are a type of lock washer that is helically split ring with open ends that dig into its partnering fastener and joint material to reduce counterclockwise rotation. Their primary function is to prevent fasteners in light-duty applications from unintentionally backing out. In a typical split lock washer application, a bolt is placed into the hole of the mating surface made of a soft material (wood, soft metals, etc.). On the underside of the surface, the split washer would be placed over the threads followed by a nut that would compress the washer against the material.