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. Note: Some images of this product may be of single cylinder version of the lock with a thumbturn on the interior rather than a keyed cylinder. Caution: Double Cylinder locks can pose a safety hazard in times of emergency due to requiring a key to unlock. Please check local codes before installing. Bored hole must be 2-1/8" Deadbolt case is formed with heavy gauge steel Solid Brass Construction Grade 1 ANSI Rating Adjustable Backset Specially-designed reinforcing strike constructed of high grade steel for ultimate strength and durability Locked and Unlocked by key ONLY from exterior and the interior side of the door. The cylinder housing is protected with a free-turning exterior cylinder guard fabricated from solid brass to resist gripping or twisting