The keyring or nanokey ring is a usable item in Deus Ex. It is an L-shaped handheld item, vaguely resembling a handgun, with a yellow grip and a purple protrusion extending past the user's hand with an LED located in the middle.
Unlike traditional keys that have been used for thousands of years, where a solid, specifically-shaped "key" is inserted into a matching aperture, this keyring uses nanites to lock and unlock doors, containers, or anything else that can be "locked" by shaping themselves into the key's shape. The keyring uses "nano keys", blue cylinders that must be collected for a keyring to access a target. The LED will turn green when a door is locked or unlocked successfully, and red when the appropriate nanokey has not been picked up, or the door cannot be unlocked by the player regardless. The nanokey is always in the player's inventory and item queue, even during the introductory training level and after they are captured by Majestic 12, and it cannot be dropped or removed from their item queue. Neither it nor nanokeys take up space in the player's inventory.