What is a characteristic of castellated nuts?

Castellated nuts are specifically designed with notches or slots that allow for a locking mechanism using a safety wire or cotter pin. The primary characteristic that distinguishes them is this feature, which enhances the safety of critical applications where nuts are subjected to vibration or rotational forces. By using safety wire inserted through the slots on the nut and a corresponding drilled hole on the bolt, this design effectively prevents the nut from loosening during operation. This characteristic makes them particularly valuable in aerospace and high-stress environments.

Other choices do not accurately describe this type of nut. While they may convey some notions about nut properties or applications, only the notch design for safetying accurately captures the essential purpose and characteristic of castellated nuts.