Entry into the pool by children, pets, or intruders is detected by the unit's electronic sensor, and sets off a loud, pulsating alarm. Safe, simple, and easy to operate, the 9-volt battery powered alarm snaps onto the top rail of your above ground pool. To store your alarm while using the pool, snap it on the outside of the pool. Poolguard comes with a remote receiver which sounds an alarm inside the home when the unit is activated at the pool. The Poolguard alarm system can be used with a solar blanket on the pool. Poolguard comes with a three year limited warranty. Meets all ASTM safety standards for pool alarms: ASTM-F2208-02 OFF POSITION ON POSITION