The 3-pole configuration means it switches all three phases simultaneously, which is the standard for three-phase motor and feeder circuits up to the rated current.
The T-MAX XT1 range uses a common mounting footprint and terminal layout across amp ratings. If you're swapping in a panel originally built around the lower-rated XT1NU3090AFF000XXX (90 A), the XT1NU3125AFF000XXX shares the same pole count and physical envelope — no busbar rework or drilling needed, just a straight amp upgrade.
