The 065966 is a versatile clamp-on lockout device for single-pole circuit breakers. Constructed from rugged polypropylene and impact-modified nylon, it uses a thumbscrew to securely clamp onto the switch tongue. A cover then pulls over the thumbscrew and can be locked in place to prevent the clamp from being loosened. Its unique blade design provides a tighter grip with less torque on the thumbscrew. This device accepts lock shackles up to 9/32" (7.1mm) in diameter and includes detachable cleats to expand the range of applicable breakers, making it a vital tool for electrical lockout programs.