They are not road legal and are stamped as for "track use only"
I have been using a Pinlock Protint my Shoei XR1100 for the past year and its ok. Not as good as a full tint pinlock insert though. Slightly darker than a clear insert in normal or dull conditions and good enough to keep most of the glare off in full sun. The benefit is that you you dont have to keep swapping it out for a clear. I took it out for the winter though.
What is is not great at is night riding or poor visibility/heavy rain. The insert is much thicker than a standard clear pinlock so you do get a bit of the double glazing effect which I find distracting in heavy rain. Also does not sit as close to the main visor as a clear one. Price is steep aswell.