The K curve trips between 10 and 14 times rated current, making it suited for motor and transformer branch circuits where inrush is higher than a resistive load but lower than a D-curve would tolerate.
Snap-on DIN rail mounting for 35 mm rail per EN 60715. Four-pole width at 18 mm per pole gives a 72 mm footprint — standard for a 4P MCB in a distribution board. The K characteristic means the breaker holds through motor starting current without nuisance tripping while still providing short-circuit protection for the branch.