Hollis M-3 Mask Visibility is the most important aspect of any dive. The new M3 mask provides that with distortion-free vision and superior fit. This low profile design uses a rigid frame and two lenses with 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. Frameless 100% Pure Silicon Skirt Saint-Gobain Diamant - Crystal Clear Lenses Wide Vision and Low Volume 4-Way Buckle Design for Superior Comfort Accessory GoPro Mount Available Separately Mask Box Included.