polyester Italy The Big Eyes Evolution Crystal mask is one of the adult high-end masks in the market suitable for scuba diving and snorkeling. Features inclined and inverted tear-drop lenses for improve downward visibility, a Cressi patented design (US 6272693). The field of view is particularly wide, laterally and in the lower zone. The lenses are made of tempered glass. The easy-to-use Integrated Buckles (Cressi patented technology) are integrated with the frame with a swivel system for quickly strap length adjustment. Made in Crystal Silicone, a Cressi trademark formula for avoiding yellowing after years.