A filler plate is a piece of hardware used in a door or door frame. In the event that one of these holes isn't needed, a filler plate can be used to conceal the hole from view and improve the appearance of the door or frame.For more than a decade, Don-Jo MFG., Inc. has provided reliable, high quality products to the locksmith industry and architectural industry. Their goal in new product development has always been to provide innovative products that will help improve the level of service and options in the ever-changing door and lock market. Today, nobody offers a wider range of products reflecting this market. Their modern manufacturing facility houses state-of-the-art equipment which allows Don-Jo to maintain stringent quality standards and to develop new products for the future. In today's ever-changing door and lock security market Don-Jo commits themselves to a program of continuous improvement.