The PelletVent Pro Cathedral Ceiling Support Box is used to support chimney pipe. Support Box may be used on flat ceilings. Trim and clamp included. PelletVent Pro is a venting system designed for stoves and inserts that use wood pellets and oil fuel. It is also built to vent corn and other biofuel products (Rated for continuous use flue temperatures up to 570? F). See all 4" PelletVent Pro Chimney Components .