The Velo XT Photochromic Sunglasses are Bliz's most technologically advanced shades for cyclists, trail runners, and cross country skiers. Ultra Lens Science makes each lens photochromic, meaning the lenses will adjust their tinting ever so slightly in order to accommodate different lighting better. Ultra Lens Science also adds maximum UV protection, oil resistant, hydrophobic, anti fog, and anti scratch convenience. The Velo XT includes three pairs of lenses for bright light, low light, and no light. These Unbreakable Polycarbonate lenses are ten times more impact resistant than standard plastic or glass lenses, and the grilamid TR90 frame is flexible, superlight, and surprisingly strong. There are adjustable nose and temple grips for a secure fit, or you can switch out the temple tips and attach the included goggle like strap for an even more secure fit.