Check the listing for details. Electric Drop Bolt Lock Security System Fail-Safe Control Easy To Install DC12V. Condition: New. Listed at 28.99 USD. Description: Made from high quality aluminium alloy material, durable to use. Secure mode: The door will lock while supplied with power, and unlock without power. With no external interference, making it more stable and safer. Especially suitable for wooden and metal doors. 0, 3, 6 seconds time delay adjustable. Specification: Material: Aluminium Alloy Working Voltage: DC12V Lock Mode: Magnetic induction Dimension: 150*34*27.5 mm Lock Mode: Magnetic induction Secure Mode: NC model ( Locked when power on, unlocked when power off ) Working Current: star-up: 1.2A, operating: 0.25A kindly note： the listing is only include one lock and it need to install Access Controller outside the door and Door Swicth inside your door Via the Access Controller power. Please kindly refer to my below attachment. Package Includes: 1 pcs Electric Mortise Bolt Lock, does not include the doorbell, power, switch button, access controller etc.