The all-new Wayne WSS30VN features an upgraded back up pump with epoxy coated steel and cast iron construction, no more plastic! the 1/2 hp primary pump moves up to 5100 gph at 0 inch of head and the combination 12-volt back up pump moves 2700 gph at 0 inch of head. Assembled in the USA and built to last, the WSS30VN protects your basement with hours of pumping power when the electricity goes out. Battery box dimensions: 9"H X 13"W X 7"L. Check valve required for install, not included in packaging.