Promate Scope Prescription Dive Mask (MK245 RX) Our Best Selling Prescription Mask ! Do you want to add readers? CLICK HERE to Add to Cart ! Ideal for standard/medium faces (universal fit) Face seal size: 4 1/2" width by 3 3/8" inches height Crystal, liquid silicone injected skirt and strap Double edge comfort seal Ultra low volume Broad peripheral view High quality Tempered glass lenses Optical lenses available from –1.0 to –10.0 by increments of 0.5 (for nearsighted or myopia) Optical lenses available from +1.0 to +4.5 by increments of 0.5 (for farsighted or hyperopia) Bifocal / Gauge Reader lenses available from +1.0 to +4.0 by increments of 0.5. (top plain without prescription, bottom with magnifier reader) How to measure your face to see if this mask fit you.If you look in the description there is a face seal size. You would need to measure the width and height of your face. Width is from one outer corner of the eye to the other outer corner and the height is from the eyebrow to under the nose. Please refer to our Prescription Masks 101 page for more information.