Clamp-on breaker lockout set includes three devices (small, medium, and large). The devices are made from durable plastic and work on a wide range of single-pole and internal-trip multi-pole breakers. The small lockout locks out 120/277 V breakers. The medium lockout locks out 480/600 V breakers. The large lockout fits on breaker switches up to 2-1/4" wide and 7/8" thick. A convenient thumbscrew allows the device to be easily secured to the breaker, which can then be locked in place with a lockout padlock. Each device accepts 1 padlock, with a shackle diameter of 0.35". Two detachable cleats are included.