Abstract: A dial for a combination lock extends through a disc mounted on the housing for supporting the dial. A pair of interchangeable members, one being used at a time, are used in conjunction with the dial. The first interchangeable member is a spacer mounted on the disc between the dial and the disc for spacing the dial from the disc and covering a portion of the disc. The second interchangeable member is a cover mounted over the disc. The cover has a window through which the dial can be seen. The window includes a lens with thin plates therein for directing light from the dial in a certain path so that the dial can only be seen from one position. The cover has members for securing the lens in the window so that it is not easily removed therefrom.

Abstract: Method and apparatus for decoding and duplicating a key wherein the notches in the shank of the key are coded to a predetermined coded depth and spacing therebetween. An index card having a sequential index thereon corresponding to the predetermined coded depth is inserted into a housing and the key to be duplicated is inserted into a slot in the housing where it engages an indexing member which enters one of the notches on the key and indicates on the card the coded depth of that notch. The angle of cut of the same notch may also be determined. The remaining notches of the key may be decoded in like manner. The same index card is then inserted into a housing which includes an indexing drum having notches therein with spacing therebetween corresponding to the predetermined coded spacing of the key to be duplicated. A blank key is firmly secured in a predetermined position on the housing and movable in a direction toward a grinding wheel.