The right HVAC system components will make all the difference. Get this discount DuraVent 6VFT-25BL Ventinox VFT Black Single-Wall, 6" x 25'. Don't hesitate to contact us if you aren't sure this is the part you need. Used for upgrading or restoring masonry chimneys that vent Category I natural gas, propane or oil appliances, wood or pellet stoves, fireplaces and fireplace inserts. Single-wall, .006” 316 Ti (Titanium) stainless steel. Continuous weld delivers a strong, air and water tight flue gas conduit.