Features photochromic lenses that lighten and darken as outdoor lighting conditions change. Designed for comfort, the glasses come with spring adjusted temples that provide a customized fit on either narrow or wide faces, a soft nose bridge that adjusts, and a nylon brow that’s easy going on the forehead. The impact-resistant polycarbonate lenses absorb 99.9% UVA and B rays. Recommended for use during chipping, chiseling, drilling, grinding, machining, masonry, pouring/casting, power fastening, riveting, sanding and sawing. Transition from light to dark takes less than 20 seconds (allowing just 22% light transmission), and dark to light takes less than 3 minutes (allowing 77.5% light transmission). Air temperature may affect the lens transition time.