The Master Lock ISO/DIN lockout, pin in lockout device, keeps an individual miniature circuit breaker in the off position during maintenance or repair projects, when used with a padlock (sold separately); it has a durable and impact resistant red polycarbonate body with steel pins that fit DIN rail mount (or ISO/DIN) miniature circuit breakers with toggle openings up to 12.7 mm between lockout holes and with lockout holes on the outside of the switch. The locking hole accommodates all American Lock Safety Lockout and Master Lock Safety Series padlock shackles and lockout hasp diameters. When used according to manufacturer"s recommendations, this product is covered by a limited lifetime warranty against defects in workmanship or materials. Circuit breaker lockouts can be used as part of a safety procedure known as lockout-tagout (LO/TO), usually required at facilities where multiple workers need access to a circuit breaker panel (or distribution board). LO/TO, as defined by Occupational Safety and Health Administration (OSHA), requires that lockout devices be durable and standardized. Lockout devices use color, warning labels or tags, and a physical barrier to temporarily prohibit machine operation or power activation, and help reduce accidents, during maintenance or repair. Circuit breaker lockouts are used to keep the electricity off in a specific circuit by securing the circuit breaker toggle switch in the off position. They consist of a lockable clamp or hasp to immobilize an individual circuit breaker switch. Some use lockout holes in the breaker toggle switches to help prevent a switch from moving, while others clamp tightly over the switch to deter manual operation. Master Lock manufactures padlocks, combination locks, and related security products. The company, founded in 1921, is headquartered in Milwaukee, WI.