We bought the system after our neighbors alerted us to some suspicious activity on our porch. We had the lock for installed for two days and everyone in the house had learned and used the code several times per day. When my teenage daughter arrived home late in the evening she immediately went up and checked the door. Seeing it was locked, she entered the code and the mechanism did not unlock. She tried again and it still would not unlock. Although the lock has a key option, we did not buy it for that so she did not have a key on her.  Unfortunately this left her outside in 20 degree weather panicking until someone could get to her. Needless to say, this lock went back and we paid the extra money for a Shlage that allows us to manually turn the lock ourselves and not rely on possible mechanism failure.