Both the Solatube 160 DS (10 in/250 mm Daylighting System) and 290 DS (14 in/350 10" (250mm) fit easily between roof rafters with no structural changes, so there is no need to build a skylight shaft.  Our adjustable tubing design includes two Spectralight® Infinity angle adaptors that allow installation around attic obstructions and Spectralight® Infinity extension tubing in 16" (400mm) and 24" (600mm) segments.  All are designed to telescope together for easy installation with no cutting necessary.