Protect Your Family from Dangerous and Potentially Fatal Electrical Shock in Water! There are multiple ways in which electrical voltage could be introduced to a pool or lake. An improperly grounded wire on a pool or dock light is just one example. When voltage gradients are present in water, the electricity will typically take the path of least resistance--through the swimmer's body. This could result in Electric Shock Drowning, potentially electrocuting the swimmer and leading to temporary paralysis and the inability to swim. Shock Alert is a handheld device that is used to detect electrical voltage in pools and lakes, and warn you of it's presence. When voltage gradients are detected, Shock Alert will provide a visual (red flashing light) and audible (loud beeping) alarm. Shock Alert will detect voltage gradients as low as 20mv/ft in concrete, gunite and vinyl lined pools. Due to the insulating effects, Shock Alert is NOT for use in fiberglass pools and hot tubs. UL 61010-1, 3rd Edition; CAN/CSA-C22.2 No. 61010-1-12, 3rd Edition