The Siemens 5SL6120-8CC is a 1-pole miniature circuit breaker in the 5SL6 Basic Devices family, rated 20 A with a D tripping curve at 230/400 V AC and a 6 kA breaking capacity.
RoHS-compliant since June 2013, and REACH candidate-list information is available from the manufacturer.
Where it goes in the panel
Snap-on DIN rail mount, single module width. Fits standard distribution boards alongside other 5SL6 series breakers. The single-pole form factor protects one phase of a 230/400 V line — use three of these for three-phase distribution, or one for a single-phase branch circuit.