I got my Energizer HardCase Work light probably three four years ago. It came with the batteries pre-installed so battery replacement was not an issue. To the credit of Energizer the batteries finally gave up the ghost. I tried every which way but loose to get that thing apart to replace the batteries. I ruined the rubber up by the lens because it is so old. I usually can figure these mechanical things out. I was stumped. I figured Energizer would have the answer. I am as frustrated as the other comment givers that information was not provided. As in the Q&A section. The instructions are in the inside. Huh!! Other than the battery issue it is a great product.