Direct Vent Fireplace Termination Cap Cover  2 Radiant Barrier Foil Made in USA Fits the Trapezoid Termination Cap shown below. Two soft twist ties hold the shield securely to the cap. An attached insert of  Energy Star approved polystyrene foam fits into the bottom screen area to close it off. This cover features an adjustable top with additional neoprene gaskets to accommodate different top vent designs. When installed the top will fit snuggly against the top of the cap. This cap has a 13  height from the bottom of the trapezoid to the flange. Cap cover is a double-sided, multi-layered industrialized-strength, lightweight solid (non-breathable vapor barrier) aluminum radiant barrier approximately 6.5 mils in thickness that reflects (blocks) 97% of the radiant heat that strikes its surface! We use RadiantGUARD radiant barrier foil and insulation products which are beneficial in ANY application where the goal is to CONTROL HEAT. When placed between a source of heat and an area you wish to keep cool, the surface of our radiant barrier