Made of high grade stainless steel. At least 8 feet of pipe is necessary to produce the optimum air-draw through the stove for a fast, efficient heating rate. A shorter length will produce a slower heating time. Using more than 8 feet of pipe produces a hotter fire but will reduce fuel efficiency because more of the flame is drawn up into the chimney. Remedy this by installing a stove damper. If more than 8 feet of pipe is used, it must be supported to insure stability. Sheet metal screws and a cobalt drill bit are provided with the Chofu Wood-fired Heater for fastening stove pipe connections.