The ABB XT1NU4015AFF000XXX is a molded-case circuit breaker from the XT1N series, rated 125 A with a TMF trip unit. It's a panel-mount device sized for a standard DIN-rail or screw-mount enclosure, common in distribution boards and motor control centers.
The lifecycle stage for this order code is listed as current, meaning ABB still produces it as an active catalog item. For a sourcing buyer, that translates to standard availability through the distribution channel — no last-time-buy clock ticking, no forced substitution.