Cressi Sky Mask and Gamma Snorkel Combo The new Cressi Sky mask partnered with the popular Gamma Snorkel. The Sky mask features a large, single tempered glass lens for spectacular visibility in all directions. Mask also features a 100% silicone skirt for outstanding comfort and fit, as well as a flexible, easy-adjust buckle system. Gamma Snorkel features a splash guard top to eliminate water entry as well as a large purge vavle for easy clearing.