The A9K23350 is a Schneider Electric Acti9 iK60N miniature circuit-breaker (MCB) — a 3-pole, B-curve device rated 50 A at 30 °C for AC networks.
Ratings that matter for the install
Rated 50 A at 30 °C ambient — that's the continuous current it carries without tripping. If your panel runs hotter, you'll need to derate per the standard thermal curves, but at typical board temperatures this holds. Insulation voltage rated 440 V AC, overvoltage category III, pollution degree 2 — all standard for fixed-installation MCBs in distribution boards.
Clip-on DIN rail mount — no screws needed to secure it. Stripping length is 14 mm; tightening torque 3.5 N.m. The toggle gives clear ON/OFF indication, and there's provision for a padlocking device to lock the handle in the off position for isolation. IP20 finger-safe terminals, so it's fine inside an enclosure but not for wet locations.