Toxic gases caused by decaying matter and fish waste can become trapped under the ice. TetraPond® De-Icer helps release harmful pond gases by keeping an area of the pond ice-free.Features:• Natural stone finish• Releases harmful pond gases• 300 watts• Energy-efficient thermostat control shuts off power when not needed• UL listed• Effective to -4°F (-20°C)• 15 foot electrical cord• 3 year limited warranty