The ABB 50 Amp Double Pole Ground Fault Circuit Breaker with Self-Test has a tin plated copper stab to create a reliable, permanent and corrosion resistant connection. The Self-Test functionality is a UL requirement on all GFCI devices commencing in June 2015. This variant of the GFCI ensures its ground circuitry is functioning properly by automatically running diagnostic testing on a periodic basis. Should a problem be detected, the circuit breaker will trip and will need to be replaced.