I wrote a message to the Aliexpress store, asking them if it indeed has a glass lens. Some Uniquefires have glass lens, some have plastic, and this does not say so. They haven't replied yet.
Ordered one anyway :-) - need two for my IR builds, so I ordered one from Gearbest ( where it says glass in the description), and the one I linked to here.
I don't actually know if it makes any difference if its glass or not :-)