The 5SL6163-6 is a Siemens SENTRON miniature circuit breaker — 1-pole, B-curve, rated 63 A at 30 °C, with a 6 kA breaking capacity per EN 60898 and IEC 60947-2. At 40 °C ambient the continuous current derates to 59.18 A; at 55 °C it drops to 52.93 A, so if the breaker lives in a crowded enclosure or near heat sources, size up or check the thermal curve. The 18 mm width (1 MW) fits a standard DIN-rail cutout; the 76 mm depth leaves room for cable bending behind the gland plate.
IP20 with connected conductors — fine for a closed panel, not for washdown. The sealable design (padlockable toggle) allows lockout/tagout without an accessory. Supplementary devices (auxiliary contacts, shunt trip, under-voltage release) can be snapped on the right side.