The A9GSB250: Snaps onto 35 mm symmetrical DIN rail. The 53 mm width (6 x 9 mm pitches) and 107 mm height fit standard enclosure backplates; depth is 70 mm, so account for that when sizing the gland plate or door clearance. Tightening torque is 2.2 N.m; strip length 10 mm. Pollution degree 3 rated — fine for industrial control panels where conductive dust is present.
The A9GSB250 is a 2-pole fuse-disconnector in the Acti9 SBI family. It's not a circuit breaker — it's a switch-disconnector that uses 14 x 51 mm fuses for overcurrent protection. The AM GG fuse curve means it's suited for motor and general-purpose protection where a gG (general-purpose) characteristic is needed. Non-padlockable, so if your safety procedure requires a lockable disconnect, this isn't it.