This is a section of Ultimate Pellet Pipe chimney. The length specified is the overall outside length of the chimney section. Each section uses 1.75" of this length when connected to another component piece of this venting system.
It is UL listed to standard UL641 as a Type L low temperature venting system. This venting system must be used with appliances requiring this venting standard. Commonly used for wood pellet burning appliances. Galvalume steel outer pipe with 300 series stainless inner pipe. 4" component pieces have 4.75" OD.
1" clearance to combustibles must be maintained when installed.