Stab-lok breakers are fully interchangeable with all past breakers and deliver the same proven quality. The unique Stab-lok breaker design of only a 1/2" thick per pole, allows for the reduction of the size and weight of the loadcentre. This breaker will work only in Federal Pioneer Stab-lok branded residential panels. Typical application for a double pole 40 Amp breaker include an electric range (240V up to 3.75kw) in a home and requiring a wire size of 8-3.