The LED bulb will never need replacing! This LED retractable keylight will always be ready to light up your keys and lock to help you get in. With the just a push of a button the super bright LED will allow you to find the right key and see all obstacles in your way. The keylight also has a 9 inch retractable cord with keyring and a handy belt clip. The keylight requires 2 CR2016 lithium batteries that are included. The keylight measures in at 4 inches x 1.375 inches x .875 inches. The LED bulb will never need replacing.