Abstract: An apparatus for use with electronic and/or mechanical access control devices includes a holder which receives a removable insert which may include an electronic module with a cover member securing the insert to the holder. The holder may take various forms and may be in the form of a key ring, photo I.D. card, etc. The holder may be a key blank for forming a key that operates mechanical locks, in which case the insert may be a dummy insert or it may include electronic components for operating various types of electronic access control devices. A method of upgrading a key for operating a mechanical lock to a key for also operating an electronic access device is provided and involves replacing the insert in the key with an insert containing electronic components. The electronic components may utilize various technologies such as proximity-based access control.