Wayne WSSM40V 1/2 hp Combination Primary and Backup Sump Pump System 120 volt primary pump - 1/2 hp pumps up to 4200 gph at 0' Tested to 1 million cycles* (Primary only). Integrated vertical float switch with solid, leak free polypropylene float for automatic operation, 9 inch ON level and 4 inch OFF level Primary pump's top suction design filters debris and minimizes clogging Alarm system, with status indicator lights, lets homeowner know when back-up system is active Designed for 15" diameter or larger sump basins 12 volt back-up pump pumps up to 3300 gph at 0'