The ABB XT5HU340AYFF000XXX is a 400 A breaking part from the XT5H molded-case switch-disconnect family, configured as a 3-pole unit with fixed front terminals and UL/CSA+TU certification. It's the internal switching mechanism — the interrupting guts — that mounts inside the XT5H enclosure, not a standalone breaker with a handle. On a panel build, this is the piece that gets wired into the line side and load side of the disconnect; the handle and shaft assembly are ordered separately.
The description reads XT5H 400 BREAKING PART 3P F F UL/CSA+TU. Breaking part means it's the internal contact and arc-chamber assembly — not a complete disconnect switch. 3P is three-pole. F F stands for fixed front terminals (the line and load connections are bolted, not plug-in). UL/CSA+TU tells you it carries UL and CSA certification plus a TU (Türkiye) market approval, so it's accepted in North American and Turkish installations without a separate evaluation.
Integration note for the panel builder
This breaking part is designed to fit into the ABB XT5H molded-case switch-disconnect frame. The fixed front terminals accept standard busbar or cable lugs; terminal torque specs follow the XT5H installation manual. Because it's a breaking part only, the handle, shaft, and door interlock are separate line items. On a DIN-rail or backplate layout, plan for the XT5H's overall depth and the handle projection through the enclosure door.