Boston Xo2Boston XO2 contact lenses are the newest technology in gas permeable contact lens technology from Bausch and Lomb. The Boston XO2 is the first contact lens to use the new gas permeable material for a Dk of 141 to offer outstanding breathability without sacrificing stability or comfort. The Boston XO2 contact lens is custom created for each client based on the specific parameters and measurements prescribed by your eye doctor. These lenses are specially designed for those with certain irregular corneal conditions. All RGP lenses are a final sale. No refunds or exchanges.