This Alpine Fireplace Glass Door reduces heat loss up the chimney by 90% when the fireplace is not in use, plus add style and function. When you're not enjoying a fire, simply close the clear tempered safety glass to minimize heat and cool air loss. This handsome accessory features a high-temperature classic black powder-coated finish and easy-grip 5in. door handles. Fits masonry fireplace openings 30in. to 37in. wide and 22 1/2in. to 29 1/2in. high. For masonry fireplaces only. Not for use on pre-fabricated fireplaces. U.S.A. Reduces heat loss up your chimney by 90% when the fireplace is not in use Cabinet-style doors with easy-catch magnets fully open to provide a full view of your fireplace Sturdy metal mesh panels 3/16in. clear tempered safety glass 1in. thick welded construction Simple do-it-yourself installation Model Number: AN-1010. Age Group: adult.