All-Metal Lock Nuts are a type of prevailing torque fastener that does not rely on any non-metallic inserts for its locking function. These nuts feature a conical top and a flat bearing surface at the bottom, with chamfered edges for enhanced fitment. The locking mechanism is achieved through the deformation of the top threads, which creates resistance against loosening due to vibration, impact, or other dynamic loads.

Designed to be installed in a single orientation (conical end facing up), these nuts are often referred to as one-way lock nuts. Since they are made entirely of metal, they offer greater resistance to extreme temperatures and chemicals compared to their counterparts with nylon or plastic inserts.