A pair of extra lenses for the ESS Crossbow series.
Made of 2,4 mm thick polycarbonate. The manufacturer promises these are totally fog-free, but we would take this with a pinch of salt. However, the coating does seem to be very good. The outside is scratch-resistant. Both lense pairs are distortion-free with 100% UVA/UVB protection. The glasses meet or exceed the following standards:
These are on the U.S. Army's Authorized Protective Eyewear List.