I have one called a journeyman (not sure of the manufacturer) and have used it for about 2 years now. It is battery powered and you press the top of the outside lens and that puts it on. Ordinarily it looks a bit weird but when you push the button it turns light. If you look at a light bulb that's bright it will dim. It was like $90 but it works very well and is very fast and is still on the original battery. It is a standard 2" by 4" lens that fits in any helmet.
It has never let me get flashed. I REALLY like it, my welding instantly got better.
