The Siemens SENTRON 5SL4120-7RC is a 1-pole miniature circuit breaker (MCB) with a C tripping characteristic, rated 20 A at 30 °C and 415 V AC. The 10 kA breaking capacity per EN 60898 tells you it can safely interrupt a fault current up to 10,000 A at 415 V AC without welding its contacts or venting plasma into the panel. That's the standard residential and light-commercial fault level across most of Europe and Asia. Rated 20 A continuous at 30 °C ambient, it carries a 1-module (18 mm) footprint, so it snaps onto DIN rail at one slot per pole.
Depth 76 mm (70 mm installation depth), width 18 mm per pole. Mounting position any.