This tempered glass is supplied by the original manufacturer and measures 20 inches by 13 inches. It is an inner door glass, designed for use in ranges/ovens and has several purposes which include providing heat insulation, acting as protective barrier, and providing an opening to monitor the cooking/heating process. Over time the glass can break or break from impact, thermal shock, or improper installation. If the glass is defective, it needs to be replaced promptly to avoid leaking, loss of insulation and potential harm to the user. Remove any fasteners or clips that secure the glass and carefully dispose of it. Position the new glass in the same position and secure it appropriately.