This is an invisible lock, which can't be pried outside the door. It achieves real keyless, don't worry about the keys lost, supporting dual unlock system, Two lock/unlock modes lock/unlock. No more drilling like deadbolt simple installation, fits for all kind of doors: wood, metal, glass, etc. very convenient. Features: No hole design, open or close with remote controllers, completely overcome traditional locks' shortcomings, realized real security. Dual system, double circuits, work independently. Using standby system to unlock when main system is broken down. Two lock/unlock modes: remote controllers lock/unlock, indoor touch manual switch lock/unlock. No drills needed, easy installation on all kinds of doors, very convenient. When the battery is low, buzzer alarm, means that changing batteries is necessary. Specifications: Host Machine: Item Type: Invisible Lock Transmission Method: Wireless, Touch Transmission Frequency: 433.92MHZ(50KHZ) Operation Range: Within 15m Unlock Mode: Remote Controller/ Indoor Touch Power Supply: 4*AA batteries (not Included) Material: Stainless Steel + ABS Item Size (With Lock Catch): Approach. 17.7 * 8.2 * 3.5cm Item Weight (With Lock Catch): Approach. 534g Remote Controller: Standard Number: 4pcs(Included) Power Supply: 1*3V CR2032 Button Battery (Included) Function: Lock , Unlock Max Controller Number: 20 (not Included) Item Size (Per): 6*3*1cm Item Weight (Per): 25g Package Size: Approx. 22.2*19.5*5.8cm Package Weight: Approx. 1076g Package List: 1* Lock 1* Lock Body Holder 4* Remote Keys 1* Bag of Mounting Screws 1* User Manual(English)