The AC-4 rating of 35 A at 400 V covers plugging and inching duty for reversing or jogging loads.
For comparison, the AC-3 rating (squirrel-cage motors) would typically be higher, but this unit's AC-2 spec is the one that governs fit for slip-ring or crane-duty applications. Exceeding it risks contact welding or accelerated wear.
The 55 mm width per unit means a row of four fits in a standard 220 mm wide enclosure section. Wire sizes: solid conductors accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) up to 2x (0.75 to 4 mm²) maximum. Stranded conductors handle 2x (0.75 to 25 mm²). The minimum permissible cross-section at 40 °C is 16 mm² for the main circuit.
RoHS compliance date is 05/01/2012, meaning the contactor meets EU substance restrictions for lead, mercury, cadmium, and other restricted materials as of that date. This is the standard RoHS declaration for Siemens SIRIUS products of this generation.