Slotted Castle Nut

Due to its comparable similarity to a crenallated parapet of a medival castle, this nut is called a castle nut or also a slotted nut.

Best applied in low torque applications, like holding wheel bearing in its place. The nut is simply fastened through the bolt, the bolt is then drilled in such a way that a cotter pin or a safety wire passes through the slots of the nut and the bolt to form a locking action