All Riffe masks are made of heat treated silicone rubber to reduce fogging. Durable Nylon frame for superior strength. The plastic and silicone mold are of the highest quality and is evident when handling the mask. The Nekton is our Lowest Volume design. It's sleek and compact. Created with the freediver in mind. The low volume skirt is comfortable and form fitting, with a tear drop glass lens shape. This offers wider vision span, allowing the diver to see more of their surroundings. 2 Tempered glass lens options: Clear Standard Amber For increased light Higher contrast Better separation in low visibility