Long There is a Bi-metal device in the base of the fan.If the surface temperature rises around 300°C, the device gently elevates the front of the fan to protect the Teg and motor and Self-Powered: Thermoelectric module acts as a small generator to power the fan's motor. No batteries or electricity required! warm air circulation results in greater comfort and reduce wood consumption from your stove Start Automatically: Upgrade technology,faster speed,larger air volume.The heat powered stove fan is designed to circulate the warm air created by a wood / coal or pellet burning.Efficiently circulates warm air throughout the house Safty Design: The stove fan is made with Anodized Aluminum, able to resist high temperature, no deformation and no discoloration even after long for time working under high temperature Newly Designed Larger Air Volume,Lower noise.You don'for t even know the stove fan is there,but you feel the warmth!You will enjoy the warm air of a quiet and comfortable environment, Manufacturer: XIAOQENAN