Placed on flue pipe, stove top or door this thermometer tells at a glance whether your stove is operating efficiently. Instant peace of mind and protection for your home and family. Thermometer works on the principle that metal expands as it heats up. It is calibrated so that the pointer on the face indicates when the woodstove is operating in a safe temperature range. This black enameled metal thermometer magnetically attaches to stove top, door or flue pipe to show at a glance if the stove is operating within an efficient burning range. Indicates overheating or a low temperature creosote buildup hazard. Stove chimneys, pipes, stove doors, stove-tops are all places where this product is useful. Every home with a solid fuel appliance needs one to monitor the safety range and efficiency of operation of the stove.