Dimensions are 105 mm wide, 181 mm high, 86 mm deep — standard SENTRON 3VA2 footprint for a 3-pole frame, so it swaps into an existing panel bucket without re-drilling the mounting pattern.
Current derating and thermal reality
Above that it starts to taper: 60.6375 A at 55 °C, 58.275 A at 60 °C, 55.9125 A at 65 °C, and 53.55 A at 70 °C. The maximum power loss is 7.9 W, which is modest for a 63 A electronic-trip MCCB; you won't need forced ventilation for a single unit, but stack several in a row and the cumulative heat matters.
What the ETU350 trip unit gives you
The ETU350 is an electronic overcurrent release that provides adjustable long-time pickup (Ir), short-time pickup (Isd) with adjustable delay, and instantaneous pickup (Ii). That adjustability is the main reason to pick this over a fixed thermal-magnetic MCCB — you can dial in the coordination with downstream breakers without swapping trip units. No communication function, no phase failure detection, no ground fault monitoring — this is a straight line-protection breaker, not a power monitoring device. If you need those extras, you'd step up to the 3VA2 with the ETU600 or add external modules.