When choosing a mask, fit and field of vision come first. The M-4 gives you the best of both worlds, fitting a wide variety of faces and offering superior peripheral and vertical vision. It is low profile, stows easy and carries an excellent value.
This lens is an extra clear glass which is valued for its attractive appearance and optical qualities. The low iron content produces a higher light transmittance and a reduced green tint inherent in other glasses. This makes the lens distortion free and helps improve color and visibility in low light conditions underwater.