Baldwin 8232 Traditional Style Double Cylinder Deadbolt Double Cylinder: A double cylinder lock is keyed on both sides of the door and is only locked and unlocked via a key. Often times they are used on doors where glass is near the door that could be easily broken and the thumbturn on a standard single cylinder lock would be accessible. Locked and Unlocked by key only from exterior and the interior side of the door. Adjustable Deadbolt.