The Siemens SENTRON 5SM9633-0 is an electronic residual current (RC) unit designed to snap onto a 5SL4 miniature circuit breaker, creating a combined RCBO assembly. It handles a rated current of 40 A and trips at 300 mA residual current, type AC (sensitive to sinusoidal AC fault currents).
Overvoltage category III means it's rated for fixed-installation downstream of the utility meter.
Standard rail mounting in any position. Depth is 70 mm, width 54 mm (3 MW), height 100 mm. The RC unit mounts above the MCB — power supply cord connects at the top. IP20 rating applies once the distribution board is installed with conductors connected; the unit itself is not sealed for wet environments.