Slots are cut across the center of the flats of a hex nut. These slots are used to secure a safety wire or cotter pin to a fastener with a drilled hole. This creates a secure hold to prevent loosening between the nut and the fastener. Castle nuts are the same dimensionally but have more curved slots cut in the top.
Our off-the-shelf slotted hex nuts start at a ¼” and go up to a 2” thread size. We carry them off-the-shelf in plain steel, steel zinc, and in a heavy pattern. Our castles nuts also come in low carbon and grade 5 steel. We have the capability to supply slotted nuts in other materials such as brass, silicon bronze, and other materials as well. KD Fasteners can turn any hex nut as a slotted hex nut as a secondary operation.