What this 2-pole B-curve MCB is for
The SENTRON 5SQ2260-0KA16 is a 2-pole miniature circuit breaker with a B tripping characteristic, rated 16 A and breaking 3 kA under both EN 60898 and IEC 60947-2 at 400 V AC. With two poles and the neutral conductor switched, it's suited for single-phase or split-phase final subcircuits where you need both line and neutral isolation in a single module. It occupies 2 width units on the DIN rail and sits at a 55 mm installation depth, so it fits standard consumer units and distribution boards without crowding.
If your fault level upstream is higher — say closer to a transformer — you'll need to step up to a higher-breaking MCB or a downstream limiting device. Energy limiting class 3 means it restricts let-through energy well, which helps with downstream cable protection and reduces arc-flash incident energy on the load side.