Features:Made of good quality zinc alloy and stable performance.Invisible remote control lock, specially designed for home security.No keyholes outside, there is no way for thieves.Tiger lock method, more safe and stable.Super design and easy for installation.Specification:Host Machine:Material: Zinc AlloySize: 15.5 * 8 * 3.5cmPower Supply: 2 * AA batteries(not included)Transmission Frequency: 433MHz500KHzOperation Range: Within 20mUnlock Mode: Remote control unlock& Mobile Phone Unlocking (additional Bluetooth adapter is required)Remote Controller:Color:SilverSize(Each): 6 * 3 * 1cmBattery(Each): 1 * CR2032 3V(Included)Standard Number: 4 (included)Maximum Controller Number: 16 (not included)Function: Lock & UnlockPackage List:1 * Lock(Not included batteries)1 * Lock Body Holder1 * Lock Catch4 * Remote controller(Built-in batteries)1 * Bag of Mounting Screws1 * USB Cable3 * Fixed Sticker1 * ManualNote:.The device beeps and flashes a red light to indicate low battery. If the battery is too low, it cannot be locked and needs to be replaced with a new battery.