DirectVent Pro Collection 5" x 8" Inner Diameter Galvanized 36" Pipe Length The DirectVent Pro 5" x 8" Inner Diameter Galvanized 36" Pipe Length is a component that is used in a typical venting installation. The DuraVent 60" direct vent pipe is designed for appliances tested and listed for direct vent. Features a fully unitized twist-lock construction in both 4"x6-5/8" and 5"x8" vent sizes. Use of sealant is optional, unless specified by the appliance manufacturer. To calculate install length, subtract 1 1?2 for each joint. No beads or hems. Black pipe lengths feature exterior laser-welded seams. Features: Inner Diameter: 5" x 8" Length: 36" Double Wall Pipe Galvanized Steel Designed for Appliances Tested and Listed for Direct Vent DirectVent Pro features tight inner connections for superb performance, with no gaskets or sealants required (unless specified by the appliance manufacturer). All black pipe lengths, pipe extensions, and elbows feature laser-welded outer wall seams for a sleek finish. Low-profile locks and no hems or beads allow for a beautiful product that looks elegant in any interior. DirectVent Pro is a unitized, coaxial venting system designed for use with direct vent gas or propane stoves,heaters, and fireplaces. Looking for Simpson Dura-Vent? You found it! Simpson Dura-Vent has changed their name to DuraVent. DuraVent is a recognized technological leader in the venting industry. Consistently the first to market with new innovations in venting systems, DuraVent has captured a leadership position in emerging markets. DuraVent has patents for several products and continues to design safe and technologically advanced venting.The company's research into solving problems with corrosion, when biofuels such as corn are used, led to the break-through patent for PelletVent Pro