DVL Collection 5"-6" Double Wall Stovepipe Increaser The DVL 5"-6" Double Wall Stovepipe Increaser is a component that is used in a typical venting installation. Use to increase from a smaller appliance flue outlet to larger diameter chimney or stove pipe. Features: Inner Diameter: 5"-6" Use to Increase from a Smaller Appliance Flue Outlet to a Larger Stovetop Diameter Height: 7" UL Listed DVL double-wall stove pipe completes the venting system when used with one of DuraVent chimney products, such as DuraTech or DuraPlus. DVL double-wall, air-insulated design reduces clearances to combustibles from 18" to 6" the closest clearance to a wall of any connector pipe. DVL improves stove performance by maintaining high flue gas temperatures for a strong, steady draft. Because the inner wall is stainless steel the flue heats up faster, stays hotlonger, minimizes the formation of creosote, and has the same life expectancy as the chimney. Adjustable lengths eliminate the need for cutting or crimping.Required for Manufactured Home installations. See appliance manufacturer's installation instructions. 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. Scientifically proven materials and unequalled engineering make DuraVent products not only the best choice, or safest choice, but the only choice for professional quality venting products.