The GE Q-Line 20 amp 1-1/4 inch Single-Pole Arc Fault Combination Circuit Breaker detects arc faults in both parallel and series wiring. The circuit breaker has a dedicated calibration screw which is cemented to prevent shifting. The attached screw creates a stable calibration for optimum performance. The unit has a tin-plated copper stab to create a reliable permanent and corrosion-resistant connection. The breaker case is made of heat-resistant thermoset for stability and structural integrity.