The M3 Mask provides visibility, the most important aspect of any dive, with distortion free vision and superior fit. This low profile design uses a rigid frame and two lenses with an ultra clear glass. The low iron content produces a higher light transmittance and a reduced green tint inherent in other glasses. This makes the lenses distortion free and helps improve color and visibility in low light conditions underwater. Optical lenses from -1.5 to -8.0 diopters available.