What the K-curve means for your load
The K-curve is designed for inductive loads — motors, transformers, solenoid valves — where inrush current can be several times the rated current. It trips magnetically at 8 to 12 times the rated current (48 to 72 A for this 6 A breaker), so it won't nuisance-trip on a motor start but still clears a hard short fast. For a 6 A rating, that's a good fit for small contactor coils, control transformers, or DC power supplies on a machine tool.
The 2-pole format takes two module widths (36 mm). Spring-cage terminals accept 0.2 to 2.5 mm² solid or stranded wire — strip 8 mm. No special busbar needed for single-phase or DC circuits; the two poles can be used as a single switched line plus neutral, or both poles on a DC supply.