This is the RX Lenses for the Mares X-Vision Mask - Optical Lens Features: Prescription mask available - item code MSK451 and MSK309 Please note there will be an additional 2 to 3 days processing time for most RX lenses Cost is per single lens only Single Lens Fits X-Vision & Liquidskin Masks, 2014 Models Improves Underwater Vision Easy to Install -1.0 to -7.0 Diopters These corrective lenses can be inserted into the X-Vision and Liquidskin masks. Available in 0.5 diopter increments from -1.0 to -7.0 for left and right lenses. Returns are not accepted for used lens. Only unused lens are eligible for return with store credit.