The AP-501 Digital Deadbolt Entry System features an auto-lock system that allows the door to automatically lock upon entry or exit. There is a master passcode and the unit allows for up to 20 additional passcodes for family, friends, contractors, etc. There is a built in intruder alarm that goes off if the door is opened without the use of the keypad or the tag fob. The lock cannot be "picked" because there is no traditional key hole. The unit also fits any standard 2 -1/8" door prep and can be easily installed with a screwdriver. The exterior unit is 6-1/4" tall x 4" wide x 1-1/2" deep, the interior unit is 5-3/4" tall x 3" wide x 1-1/4" deep and the throwbolt is a full one inch for safety. The product is warranted for 2 years and is powered by 4 AA batteries (included) and has a temporary power source of a 9V battery (not included). It is available in Aged Bronze, Satin Nickel, and Bright Brass. Also includes 2 keyless fobs. Product is manufactured in an ISO 9001 facility (Quality Management) with ISO 14001 certification for Environmental Management Systems.