This is a screw-and-snap-on mount onto 35 mm or 75 mm standard DIN rail — the same footprint as any SIRIUS S3 frame. At 70 mm wide and 146 mm tall, it'll drop into existing panel layouts without re-drilling. The front is IP20 with the cover or box terminal fitted, which is the usual protection for inside a cabinet. The terminal area itself is IP00, so keep that in mind during installation — no live parts exposed outside the enclosure.
Wiring and terminations
Screw terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²) maximum. For stranded wire, it handles 2x (10 to 50 mm²) — that's the main power feed. The control circuit terminals are sized for 2x (2.5 to 16 mm²) solid or stranded. That's plenty of lug space for a 55 A contactor; you won't be fighting undersized wire clamps.
The part is RoHS compliant per the substance prohibition date of May 1, 2012.