Radians Eclipse RXT Photochromic Lens with Black Frame Glass, Copper Photochromic Lens Glass Aluminum Alloy Frame Reverse Hinges Adjustable Nosepiece Rubber Tipped Temples Includes Neck Cord and Case RXT transition technology. RXT will darken or lighten your lens according to the amount of light. The Eclipse RXT utilizes photochromic technology. The photochromic lenses darken or lighten according to the amount of UV rays exposed to them.