ICC's UltraBlack double-wall (type E) interior venting is designed to be used as a connector between a freestanding oil, wood or coal burning stove and a masonry or metal chimney. When listed and approved by your stove's manufacturer this type of interior connector venting can reduce the required clearance to combustible surfaces as well as offering superior performance by keeping the interior stack tempertureatures higher with EPA wood burning stoves. ULTRABlack is certified for 6" clearance with the following exceptions: when designated otherwise by the stove's testing lab or when ULTRABlack is used as the connector on a mobile home certified stove the clearance is determined by the installation instructions for the specific stove model being installed. There are four primary advantages to ULTRABlack over single wall connector pipes: It offers reduced clearance to combustible materials. It is designed to last the lifetime of the stove and/or chimney system. It offers reduced creosote formation. It is certified for use with mobile home stoves. Mazzeos stocks 6" and 8" Ultra Black venting. To view complete catalog http://www.icc-rsf.com/Manuel_catalogue/XL-CAT_06-05.pdf To View Instruction Manual http://www.icc-rsf.com/Manuel_catalogue/UBII_ang-11-04.pdf