Slotted Hex Nuts

Slotted hex nuts, or castle nuts, have a hex body and slots cut near the top like that of a medieval castle.  These are used in conjunction with other fasteners like a cotter pin.  The cotter pin gets placed through the slots of the castle nut then slides through the hole of the fastener like a hex bolt with drilled hole.  These are not recommended for high vibration applications because of the shearing potential of the pin.  The total height of the slotted hex nut includes the slotted portion.