The Siemens 5SM6011-2 is an arc-fault detection device block (AFDD) from the SENTRON family, designed to mount onto an MCB 5SY60 or RCBO to add arc-fault protection in a single-module-width footprint. It's a 1P+N unit rated for 230 V AC at 50 Hz, covering a current range of 1–16 A.
Width is 36 mm (two modular units), but the design is 1P+N with one pole switched and the neutral solid; the 1 MW designation means it occupies one module width on the rail when paired with the matching 1 MW protective device. Height is 95 mm, standard for this class of DIN-rail accessory.