Selkirk 5" to 8" Male to Female Increaser (Saf-T Pipe)Selkirk 5" to 8" Male to Female Increaser (Single Wall Stove Pipe) Saf T Pipe is a heavy duty stove pipe system designed for use with residential or commercial coal and wood burning appliances. Saf T Pipe is one of the thickest and most durable stove pipes available. The welded seams assure the pipes roundness, making installation a breeze. 6" to 8" Diameters: Heavy duty construction Saf T Pipe is fabricated from 22 gauge cold rolled steel. Up to 60%