| Hex nut with slots on top of hex which resemble the parapet of a medieval castle that allign with holes in bolt or shaft to accept the insertion of a cotter pin, available in most larger sizes over M12[1/2] |
| Stock Code | Item |
| UNC.CN.1/2.SC | 1/2 UNC Castle Nut Hex BMS S/C |
| UNC.CN.5/8.Z | 5/8 UNC Castle Nut Zinc |