The Siemens 5SN6316-7CN is a SENTRON-series miniature circuit breaker (MCB) — a 3-pole, C-curve unit rated 16 A with a 6 kA breaking capacity per EN 60898 at 400 V AC. That C-curve means it trips between 5× and 10× rated current, so it handles motor inrush and transformer energization without nuisance tripping on a 16 A branch, but still clears a hard short fast enough to protect downstream wiring.
Snaps onto a standard DIN rail, occupies 3 modular width units (54 mm), and its 76 mm depth plus 70 mm installation depth leaves clearance for a standard distribution board cover.