Selkirk 208424 Support Box, 8", #8T-SBThe Support Box is intended for use when installing a Sure Temp chimney in an a frame, in a mobile home, or in a ceiling under a narrow section of roof. It provides a finished installation at the ceiling level and will support up to 20 feet of 8" diameter chimney. The part also can be used to provide shielding from insulation when installed in an unoccupied attic space. The support box assembly is comprised of a black box designed for installation