GSB633PC25 is a three-pole supplementary circuit protector manufactured by Carlo Gavazzi, designed to protect circuits against short circuit and overload currents in accordance with UL1077 standards. The device features a C-curve trip characteristic with a rated current of 25A, operating at single-phase 277VAC or three-phase 480Y/277VAC with a rated breaking capacity of 5,000A. It incorporates a bimetallic element for small overload protection and a magnetic element for short circuit protection, with an operating temperature range of -35°C to +70°C. The protector is mounted vertically on a 35mm DIN rail (EN 60715) with copper or busbar terminal connections, and includes a contact position indicator for operational status. This device is commonly used in branch circuit protection applications where supplementary protection is required in industrial control panels and distribution systems.