DG-88 1. Pure stainless steel mechanical rotationg structure enable for using more than 10 years. 2. It is very easy to change batteries in the lock,just need several minutes on ome lock. 3. Using 4x1.5V standard alkaline batteries. 4. Unlock ways:keypad or Mechanical key. 5. Keypad user capacity 300. 6. If input wrong passwords for 3 times continuously, it will stop for 15 seconds automatically. 7. Can delete the users individually who were fired.But there is no effect for the other people to use. 8. It can set up an available time for each user to unlock the lock. And the user can not unlock it in other time. 9. Very easy to install and suitable for unprofessional user to DIY (Do It Yourself),Especialy suitable for installation by non-professionals in ordinary family