I had a look at one today. They seem to be fairly sturdy, the shade adjuster knob is on the outside of the mask, goes from 9-13 plus a grinding setting.
There are delay & sensitivity knobs inside so it can be used for tig welding.
The viewing area is on the small size, similar to my first chinese mask but perfectly adequate for most people.
It has a built in light on the front & I think it uses aaa batteries.