It occupies 4 modular width units on a DIN rail, with a depth of 70 mm, width of 71 mm, and height of 90 mm — so it fits standard 4-MW cutouts in distribution boards.
The 100 A rating at AC is the nominal load current the RCD can carry continuously in a 50 Hz circuit; the derating table shows it drops to 93 A at 40 °C and 80 A at 70 °C, so if your panel runs hot, size the upstream breaker accordingly. Type A detection trips on sinusoidal AC and pulsating DC residual currents. The 300 mA trip threshold is typical for fire protection or earth-leakage monitoring on larger feeders. The 2-pole design switches both line and neutral. It is not sealable (: Sealable = No), so if your site requires tamper-proofing, plan for a separate lockable enclosure or a different RCD variant.
The power supply cord can enter from the top or bottom, which simplifies wiring in tight enclosures.