polished to provide a reflective surface or have a highly reflective metal such as silver or aluminum vapor deposited directly to its surface without the need for a separate adhesive in yet other implementations a reflective film itself may be used as a shaft substrate in such an implementation metal is vapor deposited onto the film surface or the film can include a reflective multi layer polymer composite in one preferred embodiment the shaft assembly 24 is established by a single tube however as shown in fig1 if desired the shaft assembly 24 can include multiple segments each one of which is internally reflective in accordance with present principles specifically the shaft assembly 24 can include an upper shaft 28 that is engaged with the flashing 22 and that is covered by the cover 21 also the shaft assembly 24 can include an upper intermediate shaft 30 that is contiguous to the upper shaft 28 and that can be angled relative thereto at an elbow 31 if desired moreover the shaft assembly 24 can include a lower intermediate shaft 32 that if desired may be slidably engaged with the upper intermediate shaft 30 for absorbing thermal stresses in the shaft assembly 24 and a lower shaft 34 can be contiguous to the lower intermediate shaft 32 and join the lower intermediate shaft 32 at an elbow 35 with the bottom of the lower shaft 34 being covered by the diffuser assembly 26 the elbow 35 may be angled as appropriate for the building 16 such that the shaft assembly 24 connects the roof mounted cover 21 to the ceiling mounted.