SELKIRK Sure-Temp Roof Support For freestanding fireplaces and open cathedral ceiling installations. Fits all roof pitches and requires only simple framing. Mounts easily onto top of roof through opening that allows 2 clearance. Maximum length of chimney which can be suspended below is 20'. Maximum total length is 30'. The Roof Support Kit RSK contains roof brackets and necessary hardware. The Roof Support Package RSP contains one 18 length of pipe, roof brackets and necessary hardware. The brackets may be assembled to any standard pipe length at any desired height. Locking bands must be used at each pipe joint when installing either the RSK or RSP. Clearance To Combustibles 2 , Pipe Length 18 , Inside Diameter 8 , Outside Diameter 10 , Material Galvanized Steel, For Use With Model SSII, Pkg Qty 1