The Doorgard 212LS is durable, weatherproof, and designed for both indoor and outdoor commercial and residential use. As an added security feature against forced entry, the handle will not mechanically engage the cylinder in the event of the non-recognition of an entry code.A master password control system stores and recognizes up to 120 passwords and allows for the instant elimination of unwanted users. Two mechanical keys are provided for optional use during emergency situations. The lock is powered by four AA 1.5 volt batteries (not included) designed for 15,000 keypad activations translating into approximately 5 years of usage based upon 10 activations per day. Linear PRO Access 212LS: Electronic Access Control Cylindrical Lockset is one of many Security available through Office Depot. Made by Linear PRO Access.