1 pole 15 amp stab lok Federal Pacific Electric or Federal Pioneer circuit breaker 120V plug in single pole unit 1inch thick or full size . Not interchangeable with any other.
NA15 Originally made by Federal Pacific Electric, then Challenger, then Federal Pioneer. A bolt-on version is also made called an NB type. Typically used in schools or commercial applications, but rarely for homes. Breakers were also made in the past by Federal Pioneer, American Circuit Breaker Co. and a knock off by Connecticut Breaker Co. which presently holds the rights to the brand name.
Circuit Breakers from Federal Pacific / American / FPE