Product Description The Pleasant Hearth Clairmont Fireplace Screen and Bi-Fold Smoked Glass Doors in Black finish mounts outside the fireplace opening to provide a more attractive look and reduce heat and cool air loss by as much as 90%. It features bi-fold style doors, premium mesh panels, tempered safety glass, and a one-piece frame that installs in three easy steps. Not for prefabricated fireplaces, masonry only. Made in the USA. Do not use this glass door on a prefabricated fireplace. Glass Thickness- 0.1875 inches. From the Manufacturer This Pleasant Hearth Clairmont Fireplace Glass Door reduces heat loss up the chimney by 90-percent when the fireplace is not in use, plus adds style and function. When you're not enjoying a fire, simply close the smoked tempered safety glass to minimize heat and cool air loss. Fireplace openings 30-Inch to 37-Inch wide and 25 1/2-Inch to 32 1/2-Inch high. For masonry fireplaces only. Not for use on pre-fabricated fireplaces. U.S.A.