Julbo Tensing M Sunglasses with Spectron 4 The Spectron 4 lens is a classic dark mountaineering lens, blocking 95% of the visible light; Lightweight but with excellent shock resistance Side vents bring in fresh air and stop fogging Wrap-around style protects your eyes from glacial glare Fits small to medium face Like all Julbo lenses, these lenses are optical category 1, guaranteeing 100% protection against UVA, B and C rays