4vp-36, 4" x 36", pellet stove pipe, type l vent, tested & listed to ul-641 & ul-103 standard, proven coupling joint connects in seconds to assure joint integrity, gasketed joint design, double wall design with 1/4" airspace, inner wall 304 stainless steel, outer wall paintable galvanized, rolled over male end eliminates sharp edges, 1" clearance to combustibles.