I have purchased at least 3 deadbolts for myself and I recommend them to everyone that needs a new setup. The ability to not have to use a key and never to be locked out of my house is such a relief. And with the mechanical thumbturn lock and unlock I dont have to worry about a little motor giving out one day and leaving me to go to another door or be stuck outside. The 9v battery typically lasts 3-4 years.