First off, the battery is junk. It lasts about 30 minutes before it goes dim. The bulbs that come with it are junk also. They both burn out within a week if you use it often. The only replacement bulbs I could find were Mag Light bulbs, and they throw off a huge circle of light instead of the concentrated beam that the original bulbs make. If you plan on wearing one of these on a hardhat, it's pretty bulky and flops around a lot.