The NEW MODEL PGRM-2 introduces NEGATIVE DISPLACEMENT TECHNOLOGY , a new sensing method that requires no adjustments. Entry into the pool by children, pets, or intruders is detected by the unit's electronic sensor, and sets off a loud, pulsating alarm both in the home and at the pool. Safe, simple, and easy to operate, the 9-volt battery powered alarm does not require tie-downs, ropes, or wires. 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 limited three year warranty. Meets all ASTM safety standards for pool alarms: ASTM-F2208-02