Check the listing for details. Optical Lens for IST M9 Saturn Dive Mask, Nearsighted Correction. Condition: New. Listed at 38.25 USD. Lenses for IST’s M9 Saturn mask that offer a vision-corrected view of the underwater world. o Corrective lens for use with IST M9 Saturn masko Offers diopter correction from -1.0 to -8.0 (in -0.5 decrement)o Tempered, scratch resistant glasso Left and right lenses are NOT interchangeableo Lenses are sold individually The IST Optical Lens for M9 Saturn Dive Mask, Nearsighted Correction lets nearsighted divers and snorkelers enjoy the benefits of IST’s premium M9 Saturn mask with a corrected view of the underwater world. Available in diopter correction from -1.0 to -8.0 (in -0.5 decrement). The lenses are not interchangeable, so please be sure to order the correct lens for each side of your Saturn mask. Sold individually, making it easy to select a different level of diopter correction for each eye.