1、Low voltage alarm. When the voltage is less than 5V, the red indicator will flash rapidly for 15 seconds. If it is in a low voltage state, it will give an alarm every minute. 2、Built in rechargeable lithium battery, the longest standby is up to 1 years and the maximum unlocking times is up to 1000. 3、USB charger, unlock urgently when the battery is out of power; unlocked by fingerprint after connecting the charger. 4、Never worry about losing keys, your finger is your key, bringing convenience for your life. 5、IP66 waterproof protection, durable and sturdy to withstand various environments. Features: IP66 waterproof protection, durable and sturdy to withstand various environments. Never worry about losing keys, your finger is your key, bringing convenience for your life. USB charger, unlock urgently when the battery is out of power; unlocked by fingerprint after connecting the charger. Built in rechargeable lithium battery, the longest standby is up to 1 years and the maximum unlocking times is up to 1000. Low voltage alarm. When the voltage is less than 3.5V, the red indicator will flash rapidly for 15 seconds. If it is in a low voltage state, it will give an alarm every minute. Specifications: Fingerprint head shape: Square FRR:<1% FAR:< 0.002% Identification time: < 0.5S Fingerprint capacity: 10 sets (the first two groups are administrator fingerprints) Charging current: 5V/200MA Battery: lithium battery 240mAh 3.7V(Built In) Working temperature: -20 ℃ ~+70 ℃ Waterproof level: IP66 USB interface: Micro USB 5V 0.5A (emergency + charging) Size: Shown as the picture Package Weight: 168g/ 5.8oz Package List: 1 * Fingerprint Padlock (Battery Built In) 1 * USB Line 1 * User Manual