Easy Setup; Design for Do It Yourself (DIY); No Professional Needed; Everything Included! Fit Both Left and Right-hinged Doors; Replace Most Existing Door Knobs, Easily by YOURSELF! Flexible: Master code, and upto 8 User Codes and P-Code, all Controlled by Your Own Master code. Built-in Low Battery Warning. (for single-entry room, please use SoHoMiLL YL 99 B model) Max.Security: Auto-Lock in 3-sec from Outside; Alert to Every Entry Attempt; No Phone Connected: No Hacking! No Keyhole: NO Picking!