Beeswift B-Brand Sg31 Goggle have a Polycarbonate Lens and are ideal for wearing over spectacles. The goggles have a complete contoured face seal and indirect four point ventilation. Conform to EN166:. Optical Class:1. BT - (Medium impact energy at extreme temperatures). Fields of use: - 3 Liquids, - 4 Large dust particles, - 9 Molten metal and hot solids.