It's built to protect branch circuits in industrial control panels — mechanical engineering and general industry — where high inrush currents from motor loads or transformers are the norm. The D-curve means it tolerates short-duration surges up to 10-20x rated current before tripping, so it won't nuisance-trip on a motor start or a capacitor bank energizing. Under UL 1077 and CSA C22.2 No.235 it's rated 5 kA, which covers most North American panel applications.
It takes up 4 width units (72 mm wide) on the rail. IP20 with connected conductors.