Wowtac A2S Headlamp Review 

i have had this exact headlamp for about 2 years and its friggin awesome , by far my favorite flashlight so far

I've found that the battery in mine will drain when not in use. It's great as long as I charge it just before I use it or leave the battery out when storing in my pack. Not the most comfortable head band either but it is secure. The light is bright enough to use while riding a bike at night and the burn time is impressively long when you start from a full charge. Overall it is a good value in my opinion.

I'll bet that battery is expensive to replace, especially if it's proprietary. That's my only concern.