Glentronics, Inc. DFK-961 1/3 Horsepower Basement Watchdog Submersible Combination Sump Pump System AC-powered primary pump operates as long as power is available Backup sump pump automatically begins pumping if the power is interrupted or if more water is coming into the sump than the primary pump can handle Combination sump pump system offers primary and battery backup pump capabilities User-friendly controller sounds an alarm, illuminates a warning light and describes what to do for easy maintenance Compact design fits in pits with diameters as small as 12 in.