a method for assembling a door unit installation kit , together with a container that allows the kit to be conveniently packaged and displayed . the kit includes a door , jambs and other parts , designed to permit installation of a left or right - handed door , or inward or outward opening door . the container is characterized by at least a cardboard top and cardboard bottom piece that holds these door unit parts together . the cardboard pieces are folable into place around the door unit and have cut - out portions at appropriate locations to hold the door unit part securely in place . the kit is assembled by folding and inserting tabs into locking tab inserts of the container &# 39 ; s pieces , and inserting the door unit parts therein .