Spectrum Silicone mask Micro frame construction 100% liquid Silicone with matte finish for comfort and long-life improved mold allows for sharper down view vision indented nose pocket permits easier equalization process dual tempered glass lenses flexible, easy-adjust buckles attach to tabs on the skirt enable the mask to be folded flat for packing. Spectrum 100% dry snorkel with whistle 100% dry top design to provide completely dry breathing Silicone mouthpiece prevents jaw fatigue from extended period of use ergonomic shape ideal for snorkeling advanced quick release adjustable snorkel keeper prompt clearing through bottom Silicone purge Valve built-in s.O.S. Whistle housing spectrum snorkeling fins drag reducing vented open heel snorkeling fins lightweight, flexible and durable fin blade double vent design increases speed with less fatigue quick fin strap adjustment with finger loop design quick release buckle/adjustable strap longer blade for more powerful kick (overall length: 20" for ML/XL, 18.5" for s/m) size (shoes): s/m (4.5 to 8.5), ML/XL (9 to 13).