QO and QOB one, two and three pole thermal magnetic circuit breakers provide overcurrent protection and switching on ac and dc systems. These circuit breakers have an over center, trip-free toggle mechanism with quick-make, quick break action and positive handle indication ..They also have VisiTrip trip indication, which provides a visual indication that the circuit breaker has tripped and interrupted the circuit. This QO mini circuit breaker accessory is a clamp device used on 1 pole breakers.