SKILCRAFT®120/277V Clamp-On Circuit Breaker Lockout fits circuit breakers 9/16'' W x 3/8'' L. The lockout measures 1-3/8"H, 2''L, 7/8"W and accommodates 1 padlock, with shackles up to 9/32". The thumbscrew feature allows the device to be installed quickly and easily. The lockout is made from durable plastic (polypropylene) and nylon.