Basement Watchdog Maintenance Free AGM Battery, Is Completely Sealed, For Years Of Reliable Service For Your Battery Back Up Sump Pump System Without Having To Add Battery Fluid Or Distilled Water, Compatible With Most Basement Watchdog Systems Including The Basement Watchdog Emergency #Bwe, Basement Watchdog Combination #Dfk961, Basement Watchdog Special+ # Bwsp+ & Basement Watchdog Big Combination Sump Pump System #Bw4000 With Special + Backup Controller, Will Run The Various Basement Watchdog Sump Pump Systems Intermittently For Days, Connect 2 Batteries To Increase The Run Time, Bwsp+, Bw4000 With Special + Back Up Controller, Parallel Jumper Cables Required, Not Included..