I was pleasantly surprised by this item. The light beam is bright although I had a minor issue with the units. Due to a misalignment issue, most of the beam missed the mirror. I was able to overcome this by warming the stem with hot water and applying gentle pressure. Problem solved. I found the anti fog feature claim to be true for the most part.
For those that are curious and want to know if the batteries are replaceable, the answer is yes. All that is needed is a micro mini philips (star shape) screwdriver bit.