What you're actually holding
The ABB ACS355-03E-08A8-4+B063 is the +B063 option-configured build of the ACS355 vector-inverter family, catalogued under Motors & Motor Controls / Drives / Motor Drives. The '+B063' suffix is an ABB factory option code layered onto the base drive, so the order code — not the base ACS355-03E-08A8-4 — is what has to clear the BOM line and the receiving inspection.
Reading the physical envelope
Mass on the listing is 3.81 kg, so a single tech can lift it onto the backplate without rigging; that's a handling line, not a sizing argument. Once it's in the cabinet the thermal and SCCR curves on the data sheet are what govern the panel layout around it — the kilo figure itself doesn't.
How it sits against the related ACS320 / ACS310 builds
The closest family siblings on the desk — ACS320-03U-38A0-4 at 4.40 kg, ACS310-03U-26A8-2 at 2.90 kg, and ACS310-03U-50A8-2 at 5.08 kg — are different current/frame ratings on the same ABB drive platform. They are not panel-swappable with the ACS355-03E-08A8-4+B063: the base current code, voltage class, and frame size all change between the -03E-08A8-4 string and the 03U-38A0-4 / 03U-26A8-2 / 03U-50A8-2 strings, so a drop-in replacement would need a full re-spec, not just a wiring check.