Siemens quadplex type QT breakers are a 1/2-Inch frame per pole and are suitable for use in Siemens panels that allow CTL type QT breakers. This breaker has a double pole 15 and double pole 50 Amp breakers in one 2-Inch housing. 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.