The Master Lock Grip Tight circuit breaker lockout is a red powder coated steel and reinforced polymer locking clamp that tightens with a thumbscrew then clamps down for a firm grip on most circuit breaker sizes and combines with a padlock (sold separately) to keep individual circuit breakers in the off position for safety during maintenance or repair projects. The clamping arm covers the thumbscrew to help prevent inadvertent loosening and has a locking hole that provides the ability to temporarily prohibit access to the circuit breaker with a padlock. 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 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.