Photochromic

One lens from a dark start to full sun. The tint reads UV rather than brightness: the X63 runs from 89% light transmission at dawn down to 10% at noon, the KE9022 from 85% to 15%, and the K9023 holds 85% at night, 35% under cloud and 11% in direct sun. Three TR90 frames, all UV400. The KE9022 includes a clip-in prescription frame, the K9023 ships as a four-lens set for days when you want the tint fixed.