Castle Nut: Slotted Castle, Std Hex, 5/8"-11 Thread Size, Steel, Grade 2, Zinc-Plated, 25 PK

Slotted and castle nuts feature slots cut into the body of the nut. These slots allow a cotter pin to be inserted through a hole in the male fastener, preventing the nut from unintentionally loosening. Castle nuts have slots in an elevated crown for use where clearance is limited.