What it is and what it does
The Schneider Electric A9P42625 is a miniature circuit-breaker from the Acti9 iC40 range, rated 25 A with a single protected pole and neutral (1P+N). It uses thermal-magnetic trip technology with a B curve — magnetic tripping between 3 and 5 times In — so it's sized for residential and light commercial distribution circuits where inrush from resistive loads or small motors stays moderate. Breaking capacity is 6 kA Icu at 230 V AC per EN/IEC 60947-2, and 4500 A Icn per EN/IEC 60898-1. That's enough for most panelboard applications where the prospective fault current stays under 6 kA; if your service entrance has a higher available fault, you'll need an upstream current-limiting device.
Mounting and integration
Clip-on mounting to DIN rail, 2 x 9 mm pitches (18 mm wide), so it occupies one standard modular slot. The 1P+N format puts the neutral on the left; the toggle control and ON/OFF plus trip indicator give clear local status. Tunnel terminals accept up to 16 mm² rigid or 10 mm² flexible, with a tightening torque of 2 N·m. IP20 on the terminals, IP40 on the modular enclosure — fine for enclosed distribution boards; not rated for washdown or outdoor exposure without a secondary enclosure.