Keyless lock (electronic keypad lock), install it yourself! don’t worry about losing, forgetting, or making extra keys time and time again! install this keyless door lock yourself — with nothing more than a screwdriver. Fits in standard door knob installation hole — adjustable latch backset 2 3/8″ to 2 3/4″. you’re free to add, change, or delete user Codes — and come and go as you please. This lock works for exterior, interior, side, or garage entry doors. For family, each member can have their own user code to access. Coming home late at night no problem! the keypad is lit up by energy efficient LED when pressed, so you can see it in the dark. If relatives are visiting, set a temporary code for their stay. No spare keys needed! going for a jog or a ride no more carrying a bulky key chain or worrying about losing your keys along the way. Press your code and you are home! pet lover this lock will allow you to give your neighbor or pet sitter a code of their own while you are away. When you return, simply delete the code from the lock. For rental or vacation home owner, this will reduce your costs in replacing locks and making extra keys. Install this lock on your rental property and save yourself the hassle, too. When your renter moves out, simply change the code. Please note: four aaa batteries not included: taken out to comply with transportation regulations. ! ! ! caution ! ! ! the most common error in installation: four batteries are not placed correctly. Please check the +/- poles for all four batteries according to the battery-box markings. Before installations, please read faq.