The 1P+N design (one protected pole plus a switched neutral) fits single-phase final circuits where the neutral is switched with the line. The higher 20 kA figure gives headroom for industrial panels where prospective fault current may exceed 10 kA; the 10 kA rating is what a residential final-distribution board typically requires.
Depth is 70 mm, height 90 mm. Supply can enter from the top or bottom. The IP20 rating applies only when the distribution board is installed and conductors are connected — this is normal for a panel-mount device; it is not rated for standalone outdoor or washdown use. Rated for 50 Hz supply only, 240 V AC. Mounting position is unrestricted.