The Schneider Electric A9F05103 is an Acti9 iC60N miniature circuit breaker — a 1-pole thermal-magnetic MCB rated at 3 A with a D tripping curve. It also carries a 6 kA Icn rating at 230 V AC under EN/IEC 60898-1, which is the standard for domestic-style MCB performance. The 3 A rating is sized for a small branch circuit — lighting, control transformer primary, or a single motor starter coil.
Snaps onto a DIN rail — 2 x 9 mm pitches wide (18 mm), 91 mm tall, 78.5 mm deep. That 78.5 mm depth is the dimension you need for enclosure fill-factor and gland-plate clearance; it fits standard 80 mm deep enclosures with a few mm to spare for wiring. IP20 rated — panel-internal only, no washdown exposure.