Plus corrective lens to fit TUSA Ceos, Geminus, Splendive IV or Splendive II masks. PLEASE NOTE: These lenses are sold singularly, please order one for each eye. These lenses are bi symmetrical & can fit in either eye, however we sell them as a right & left lens to aid with fitting into the mask. IF YOU REQUIRE YOUR LENSES TO BE FITTED PLEASE PURCHASE THE LENS FITTING SERVICE BELOW. Specifications The measurement you need from your prescription is the Sphere measurement. Optical lenses will replace the original lenses fitted to your mask. If you want to fit prescription lenses to one of TUSA's Pro Masks you willl loose the Anti Reflective & Ultraviolet benefits of their lenses.