Safety Turtle works with ALL Fresh Water, natural [lake, river and pond] or man made [pool, hot tub and pond]. A loud alarm instantly sounds at the Base Station when the Turtle is immersed in water. The alarm continues to sound until it is reset. The Safety Turtle system can be progressively expanded through the purchase of additional sensors(s) of the same color The Turtle has a battery life of 3 - 4 years. Base station battery pack sold separately.