Hillman Zinc-plated Steel All Metal Nut

Commonly known as stover nuts, top lock nuts feature chamfered corners and a conical top. The distortion in the top threads resists loosening from vibration. This unique design feature works by applying force against the bolt, protecting the nut from loosening. Also called one-way nuts, top lock nuts can only be installed one way and are often used in high temperature applications because they are all metal with no nylon insert.