DuraTech Class A Finish Collar 5" to 8" Size:6 in. The 4" Selkirk Adjustable Flashing The 4" Selkirk Adjustable Flashing is the best way to waterproof where the pipe comes through a shingle roof The distance from below the horizontal tee snout to the bottom of the tee body is 3 4" The DuraTech Finish Collar simply twists into the male end of the DuraTech pipe and reduces down to a single wall pipe end The DuraTech Finish Collar is used to make the transition from the DuraTech Class A chimney pipe to single wall stove pipe for through the wall applications and when the chimney pipe is suspended with a roof support system