3"D x 12"L, Adjustable Pellet Vent Pipe, Fully Unitized, Twist Lock Construction, Adds 3"-10" Length, Both Vertical & Horizontal Installations, 3-5/8" OD, Designed For Stoves That Burn Wood Pellets, Double Wall & Air Insulated Pipe, Inner Wall Of .012" Super Ferritic Stainless Steel, Outer Wall.018" Laser Welded Galvalume, Patent Pending Venting For Stoves & Inserts That Use Wood Pellets, UL Listed For 3" Clearance To Combustibles In USA & Canada.