This is the Cressi Air Crystal Silicone Skirt Two Lens Mask for Scuba Diving Snorkeling Features: Crystal Silicone U.S. Pat 6272693 B1 Double injection technology Integrated dual frame Tempered glass Micrometric adjustable buckle Flexible buckle Inclined lenses This mask has a particular tapered structure deriving directly from the highly popular Nano-mask patent. The Dual Integrated Frame Technology System allows you to join the silicone skirt to the lens frame without major interruptions of the curvature continuity. The result is a mask with an extremely hydrodynamic shape and, visibility being equal, a significantly smaller size. The field of view obtained is particularly wide, laterally and in the lower zone. The skirt, in the front part, has a structural silicone insert which increases the sealing ability of the mask and creates an exceptionally pleasant chromatic play. Micrometer adjustable buckles.