The DuraVent 4PVP-X8 is a chimney adapter designed to be used to transition between your pipes to your existing chimney. This belongs to the PelletVent Pro collection that is applicable for biofuel vent system. It measures 4-8 inches inner diameter and has a length of 7 inches. It is also a quality product as it is made to be corrosion-resistant and is a UL-listed product.DuraVent is a highly trusted brand for your venting systems. Whatever you need, they got it for you. Get yours now here at PlumbersStock.com!