The Schneider Electric G12E4F125 is a GoPact MCCB 125 — a 4-pole molded case circuit breaker rated 125 A at 40 °C, with a 15 kA breaking capacity at 415 V AC (performance level E). It uses a TM-D thermal-magnetic trip unit providing LI protection: thermal for overload (L) and magnetic for short-circuit (I). That makes it a straight distribution breaker for panelboards and sub-distribution boards where you need a fixed, non-interchangeable trip curve. Rated operational voltage is 415 V AC 50/60 Hz, with an insulation voltage of 440 V AC, both per EN/IEC 60947-2. It's also certified for isolation (suitability for isolation: yes per the same standard), so you can use it as a visible-break disconnect in a distribution circuit.
Connection pitch is 25 mm, with front-facing screw terminals on both line and load sides. Neutral is on the left, and the 4D protected poles cover all four poles with neutral protection set at 1 x Ir. Dimensions: 100 mm wide, 130 mm high, 60 mm deep. That's a compact footprint for a 4-pole 125 A breaker — fits standard distribution panel layouts without crowding adjacent devices.
If your service entrance has a higher fault level, you'd need a higher-rated MCCB upstream. Electrical durability is 5000 cycles at rated current and voltage; mechanical durability is 30000 cycles. That's typical for a distribution breaker — not designed for frequent switching like a contactor, but fine for occasional manual isolation and automatic fault clearing over the life of the panel. That's the standard for most enclosed industrial panels — no special derating needed for normal factory environments. Power dissipation per pole is 18.7 W. Factor that into your panel thermal calculation.