Hi-collar lockwashers are similar to standard split lockwashers in that they have a split in the center of the washer with turned up ends to bite into the mating material but these washers are made to be used with socket head cap screws. The outside of the washer is designed to line up perfectly with the bottom of the head of the socket head cap screw so that there is no overlap or extra material. Hi-collar lockwashers are made from heat treated, medium carbon steel.