This adjustable radiation shield may be extended to suit the joist height and is set at a diameter to fit between the outter flue casing and the joist box. Should be used in conjunction with a Ventilated Fire Stop.   PLEASE NOTE - We recommend a minimum of 1 metre vitreous flue pipe LINK is installed between the stove and stainless steel twin wall system.  Your vitreous flue pipe will either be 5\" or 6\" depending on which stove you have purchased.  Each stove product page has a link to which of the two stainless steel flue connectors you will require for your installation. All stainless steel twin wall flue systems are 6\" (150mm) in diameter.