Fangrui Product Details Ultra-long Battery Life;with A Battery Life Of More Than One Year, There Is No Need To Frequently Batteries. This Long-lasting Not Only Improves The Convenience Of Use, But Also Greatly Reduces Maintenance Costs And Troubles. Check History Records;the History Of The Open/close Record Be Displayed In The History Records Of The App, Real-time Monitoring Of Your Property Security. Requirements For Installation;please Note That The Thickness Of The Lock Body Should Not Exceed 28mm. This Distance Is To That The Lock Body Can Sense The Ic Card And Unlock Smoothly. Reliable Fixation;the Fixation Of Stickers And Screws Allows The Lock Body And Buckle To Fit More Firmly To The Cabinet Door, Ensuring Safety Of Use. Technical Specifications: Unlocking Methods Supported: Mobile Phone Bluetooth/card Number Of Users Supported: Card Users: 250 Local Management Function: Supported Supporting App: , Power Supply: 4 No. 7 Alkaline Batteries (not Included) Working Current: Less Than 50ma Working Temperature: -20