Siemens QPJ breakers are intended for use only in Siemens EQIII three-phase load centers from 125-400 Amps. The breaker takes up six 1-Inch breaker positions, three on each side of the panel. Siemens strongly recommends against the use of “used” breakers. The installation of used breakers in a Siemens panel will void the warranty on the panel. Siemens does not sell used breakers and has not approved any 3rd party sellers to do so.