ORIGINAL KD's. KD's glasses KD's are appreciated for KD's or X-KD's Even the arms lengthen from 5.28 in for KD's to5.82 in for size XL. Each KD's has its X, if you hesitate, ask ! The diversity of choice: polarized lenses, mirror lenses, special lenses for presbyopes who can thus read a map, photochromic lenses.