I have one of the ones that used to be expensive. There is no battery but I have an adjustment dial that goes from 9 to 13. I can tell you that they are quite amazing. It is possible to position your head such that the sensor gets blocked and it doesn't darken. In my case, this results in me seeing a bright green ball with no detail. However I do not get any after affect, I just stop right away and try a different position. I have never had any eye problems from welding and I am close to completing an entire cab rebuild.
When I was looking at helmets, I took the flash from my camera and used it to evaluate the response. With one of the cheapies it was just like looking into the flash with no helmet. With my present helmet I could clearly see all the details inside the flash lense.
