Toxic gases caused by decaying matter and fish waste can become trapped under the ice by releasing harmful pond gases. The De-Icer helps release harmful pond gases by keeping an area of the pond ice-free. Features include a natural stone finish. 300 watts. Energy-efficient thermostat control shuts off power when not needed. UL listed. Effective to - 20°F (-28.8°C). 15 foot cord. 3-year limited warranty.