FI block, 4-pole, type A, In: 40 A, 300 mA, Un AC: 400 V, for 5SY FI block SENTRON 5SM2 for combination with miniature circuit breakers for personal, fire and line protection. The combination of the FI blocks with miniature circuit breakers is possible without tools by simply plugging them together. The variety of types of FI blocks and the extensive range of miniature circuit breakers offer a large number of combination options for all your applications. All FI blocks 100 A and 125 A have external remote tripping via connection terminals Y1/Y2, which can also be used to implement central OFF circuits. All additional components for miniature circuit breakers can be retrofitted on the right-hand side. Optimum technology for your safety - only from Siemens.