The MGN60508 is a Schneider Electric C60N miniature circuit breaker from the Multi9 range, rated 3 A with a D curve. The 10 kA Icu at 240 V AC (phase-to-neutral) tells you this breaker can safely interrupt a fault up to that level without damage; the 3 kA Icu at 415 V AC is the limit for higher-voltage single-phase circuits. That matters for commercial and light industrial BOMs where the panel design calls for Category A utilisation and isolation capability (this one carries both).
One-pole wide at 18 mm (2 x 9 mm pitches), so it occupies a single module slot. Depth is 73 mm; height 81 mm. Tunnel terminals accept 1…25 mm² rigid or flexible wire; strip length 14 mm, torque to 2 N·m. The toggle gives local ON/OFF indication.