What this cradle does in the MasterPact system
The LV839335 is the drawout cradle for a MasterPact MTZ2 breaker — the fixed chassis that the breaker mechanism slides into. It carries the 4-pole main contacts and arc chutes, rated for 800-4000 A at 40 °C ambient. The cradle is the part that stays wired to the bus; the breaker unit itself racks in and out for maintenance or swap without disturbing the power connections.
Drawout mounting means the cradle bolts into the switchgear cubicle, and the breaker slides in on telescoping rails. The 4-pole configuration handles three-phase-plus-neutral or three-phase-plus-switched-pole applications. UL/ANSI listing confirms acceptance for North American panel builds under NEC and CEC.