This patented underwater wave detector alarm guards your pool while eliminating false alarms from wind or rain. The sensor discretely mounts inside the pool and detects when objects weighing 15 lbs. or more enter the water. You can also adjust the sensitivity. The alarm emits a loud siren at the control panel mounted on the pool or nearby. The control panel has an on/off switch, low battery alert and power check reset button. Easy to install and operate. Maximum Pool Size 24 ft. round or 16 ft. x 32 ft. oval. Comes complete with mounting hardware and instructions. Requires 4 'AA' batteries (not included). Backed by a 1 year warranty.