Clamp-on breaker lockouts are easy to install using patented thumbscrew design - no screwdrivers needed. Simply tighten lockout securely onto switch tongue, pull cover over thumbscrew and lock cover to prevent clamp from being loosened. Included detachable cleats expand the range of applicable breakers. Made of rugged polypropylene and impact modified nylon. Cleats are included (#65404) for use with breakers with long, sliding switch throws.