QO 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. A full line of features and factory installed accessories are also available such as shunt trips, auxiliary switches and alarm switches. QO circuit breakers are UL Listed and CSA Certified.