RX CLEAR SNORKELING SCUBA MASK PRESCRIPTION LENSES PRESCRIPTION MASK FOR SNORKELING AND DIVING THAT FITS MOST FACES Mask includes 1 premade drop in prescription lens for each eye. Pre-ground and inserted into your mask in place of the standard flat lens Distance Problem RX's Only -1.0 to -10.0 Diopters Comfortable high quality Mask with Soft silicone skirt