The Square D QO Value Pack 200 Amp Main Breaker 42-Space 42-Circuit Convertible Indoor Plug-on Neutral Load Center with Plug-on Neutral breakers is UL listed for residential, commercial and industrial power distribution. Engineered for a quick Plug-on Neutral breaker connection on every circuit, fewer connections, faster installation and no pigtails frees up gutter space. Accommodates plug-on secondary surge arrestor (sold separately). Overhead/underground feed simply by rotating the device before installing. Rated 120/240 VAC and 22,000 AIR short circuit current rating.Designed with straight-in mains to save expensive cable and time. Split branch neutral with terminal screws backed out offering with up to 50% more terminals than UL requires increases wiring flexibility saving installation time and simplifies wiring.