The Sun-Tek Self Flashing Aluminum (SFA) model allows for placement of drywall inside of the curb. Note that the base is one solid piece of aluminum ? it can't possibly leak. Foam insulation, designed to provide thermal protection, is built into this model as well. The special flange ridges are really important. They're patented Water Diversion Channels that guide water off the skylight to prevent leaks. You only get them on a Sun-Tek Skylight.