Square D™ I-Line™ Panelboard Interior, Main Lug, Series: NQ Series, 400 A, 240 VAC, 3 Phase, 4-Wire, 42 Spaces, QOB/QOB-VH/QHB Circuit Breaker, Copper Bus, 50 in H x 20 in W x 5-3/4 in D
Square D NQ main lug interiors accept plug-on and bolt-on circuit breakers.