Siemens 5SL3120-7MB SENTRON MCB — 20 A, C-curve, 1-pole
It breaks fault currents up to 4.5 kA per EN 60898 at 230/400 V AC, which covers the standard residential and light commercial fault-current duty in most European and Asian installations.
The C-curve means the magnetic trip fires at 5 to 10 times rated current — 100 A to 200 A for this 20 A breaker. That suits loads with moderate inrush, such as lighting banks, small transformers, or resistive heaters. The IP20 protection with connected conductors means the terminals are finger-safe only when wired; the breaker itself is not sealed against moisture or dust ingress.
The 18 mm width (one modular unit) and 70 mm installation depth mean it fits standard distribution boards and sub-distribution panels without projecting beyond the enclosure depth.