Lord only knows how much ultra violet is getting thru. Better is the glass for a welding face shield. Be sure it is firmly attached to the front of the binoculars. I both wire it on and tape it. Keeps the light and heat out of the binoculars. I forget what number welding glass is needed, but I'm sure others can advise you. Be careful! When in doubt, don't.
I'm not a hardnosed mainstreamer; I just like the observations, theories, predictions, and results to match.
"Mainstream isn’t a faith system. It is a verified body of work that must be taken into account if you wish to add to that body of work, or if you want to change the conclusions of that body of work." - korjik