PERIMETER ALARMSinfra-red pool alarm, which use laser or infra red light, form an unbroken beam of light around the pool’s perimeter. When someone entering the perimeter breaks the beam the alarm sounds. Alarm beams are positioned 12 to 24 inches above ground level and should be adjusted according to your child’s height. These devices, which are the most expensive on the market, give total perimeter protection at a set height. Disadvantages are that the set height may not suit visiting children and that the alarm will activate if one of the pool’s perimeter alarms is inadvertently hit, moved, or covered. WRIST ALARMS These versatile alarms, which are the latest in water safety, may be used at the pool, in a boat—- anywhere there is fresh water. These waterproof devices are key locked securely onto your child’s wrist and communicate via a base station. When the wrist alarm is immersed in water the station alarm is activated. Base units and wrist alarms are purchased separately, which means you may have numerous wrist alarms for one base station. The wrist alarms have become very popular. To outfit three children the cost would be approximately $250. Some disadvantages are that they must be on your child’s wrist 24 hours a day to be totally effective, separate units must be purchased for visitors to ensure their safety, and they do not function in salt water.