CROSSBOW Unit Issue, NSN is 4240-01-583-5742 by ESS Advanced ClearZoneTM FlowCoat lens treatments eliminate fog inside & prevent scratches outside Tri-TechTM Fit temples achieve a universal fit with max comfort & zero pressure points DedBoltTM Lens Lock keeps lenses secure under impact yet easy to swap Ballistic 2.4mm high-impact polycarbonate lenses Lenses are interchangeable & provide 100% UVA/UVB protection