It's a Type AC unit — designed for sinusoidal AC residual currents — and sits in a standard 2-module-wide DIN-rail cutout. The 70 mm depth matches the common SENTRON panel profile, so it aligns with the busbar and outgoing terminals in a distribution board without projecting past the gland plate.
The 63 A AC rating is the continuous current it carries in a 40 °C ambient — at higher enclosure temperatures the load must be derated: 58.6 A at 40 °C, 56.7 A at 50 °C, 50.4 A at 70 °C. The 300 mA residual-current sensitivity is a fixed, non-adjustable trip point; this is a protection device for equipment or fire risk, not personnel shock (that would be 30 mA or lower).
The 70 mm width occupies two modular-width units on the rail. IP20 rating applies only when the distribution board is installed and conductors are connected — this is an open-back device, not a standalone enclosure. Sealable? No — no provision for a lead seal or lockout hasp on the housing.