Abstract: A key retaining device that secures the functional section of the key while leaving the non functional section exposed for easy identification. The device is able to lock individual keys on a large key chain without interference with the non locked keys. The key can only be removed with the use of a master key. The device's simple and inexpensive design includes only five components: namely a housing to enclose the key, two deformable substrates, a unique set screw, and a master key. There is a bore inside the housing that runs longitudinally within the housing. The bore has a threaded section that contains the screw and a non-threaded section that contains the two deformable substrates. There is a blind slot at the base of the housing which runs from one side of the housing to the non-threaded section of the bore. The functional section of the key is placed through the blind slot, into the non-threaded section of bore, and between the two deformable substrates.