The GFR2B25300 from Altech is DIN rail mount ground fault relay (with overload protection) GFR series with 1 pole + N, B trip characteristic and 300mA ground fault sensitivity level. This circuit breaker has 25A current rating, 277VAC voltage rating and 50/60Hz rated frequency. Designed to provide protection against overloads and AC ground faults (residual current faults) as well as pulsating DC ground faults. Short circuit withstand rating is 10kA.