Schneider Electric - A9F44350 Acti9 iC60N 3P C 50A MCB.
This Acti9 iC60N is a low voltage miniature circuit breaker (MCB). 
It is a 3P circuit breaker with 3 protected poles, 50A rated current and C tripping curve. 
The rated short circuit breaking capacity goes up to 20kA at 220VAC to 240VAC conforming to EN/IEC 60947-2 standard and 6000A at 415VAC conforming to EN/IEC 60898-1 standard. 
This miniature circuit breaker protects circuits against short circuit and overload current. 
The dimensions are (W) 54mm x (H) 85mm x (D) 78.5mm. 
The weight is 0.375kg.