My husband and I have purchased a home in northern Wisconsin. The house has a Schlage deadbolt on the kitchen door that holds a 9 volt battery. It uses a traditional key as far as we can tell. I don't think we have the key but the deadbolt does turn manually from the inside and we do use it at night. Other than a normal sized lock, the rest of the unit is quite large. An overall size of about 3" x 5". The cover on the inside of the house comes off and a 9 volt battery can be installed. After we did that there is a small black button on the top of the unit (inside the house) that can be pressed and the unit beeps twice. I think that we had to put it in a locked position for it to beep. It's not a terribly loud beep. Not like a sound that would scare intruders off. And I really do not see anything else that it does like activate or trigger a sensor elsewhere. We guesstimate the lock was installed around eighties time frame; give or take a few years. Our question is; What is the purpose of the battery and the beep? Thank you. skbamash@aol.com