The 5SV4311-0KL is a 1+N pole RCD breaker with a 16 Amp rated current, 30mA tripping current, 230/400VAC, a DIN rail mountable housing, and an IP20 degree of protection from external objects and dust. It is manufactured by Siemens. An RCD breaker, or in this case residual current device, is designed to detect unusual current flows in the live electrical cables, and disconnect the power supply in order to prevent short circuits. In this case, the 1+N pole indicates that 1 pole is dedicated to the live line, and the other is for both the neutral and protective earth. The 16 Amp rated current allows for a maximum of 16 Amp flowing through the line, and the 30mA tripping current will disconnect the power supply if 30mA or above is detected. The 230/400VAC indicates that both 230V and 400V are supported, while the DIN rail mountable housing provides a fast and secure installation option. The IP20 degree of protection provides protection from dust and objects larger than 12.5 mm.