Air drills have either a keyed or keyless drill chuck, which is the part of the drill that holds onto the bit. Keyless drills do not require a chuck key to tighten and loosen the jaws to remove or place a drill bit. Workers today prefer keyless drill chucks because of the convenience of not having to keep track of a key and the time it saves to change the bit. The disadvantage to this type is that most keyless drills can only be spun clockwise.