From the FasNSeal collection, designed for use on natural gas or propane-fired appliances, brings to you the DuraVent W2-1220 double wall vent length. This wall vent length is used for venting Categories II, III and IV special gas burning appliances. It has an inner diameter of 20-inches and a length of 12-inches. It is also made of AL29-4C, a special type of stainless steel that resists corrosion and cracking.This DuraVent W2-1220 wall vent length is UL listed and is covered with a limited lifetime warranty.DuraVent continues to provide its customers innovative quality products. Search one that you need for your ventilation here at PlumbersStock.com.