(Overlap Fit Only) Please see pictures above for measuring explanations. The Zero Clearance design provides air gaps between each glass panel, to ensure proper airflow required by firebox manufacturers. These doors are designed for an overlap fit, which will be approximately 1/2" on all four sides. 1" Anodized aluminum frame ensures finish protection as well as heat resistance. Trimless "full-fold" bifold doors open a full 180° for beauty, enhanced viewing, easy cleaning and safety. Door features a 3/16" tempered safety glass for strength and durability. Fully assembled and ready to install. One year warranty, including glass. The Rainbow Series Doors are strictly for Zero-Clearance (prefabricated) fireplaces doors are not intended for masonry fireplaces. These doors are also not intended for vent free fireplaces or fireplaces with vent free gas logs. Orders are non-cancelable after 24 hours. Lead time 15-20 Business days. WARNING: These doors are custom made to firebox opening size YOU provide. It is the buyers/purchasers responsibility to supply the correct firebox opening size. Doors will be custom made at time order is placed and can not be returned.