The Siemens 5SL3216-7CC is a SENTRON miniature circuit breaker — a 2-pole (2P) unit with a C-curve trip characteristic, rated 16 A at 400 V AC, and a breaking capacity of 4.5 kA per EN 60898 and IEC 60947-2. That's a standard footprint — it clips into any 35 mm DIN rail enclosure and leaves room for busbar combing and downstream wiring.
The 2-pole design switches both phase and neutral (no neutral switching on this variant — it's a 2P breaker, not a 1P+N). Halogen-free and silicon-free construction, so it's suitable for clean-room or sensitive-environment panels where outgassing matters.