Designed for full face coverage, this Sea Vu mask prevents water touching your face while you’re snorkeling. The unique mask allows natural breathing through your mouth or nose and has a wide lens for superior viewing underwater. The 100% dry-top snorkel keeps water out of the tube during your adventure. Streamlined mask is made with a comfortable silicone skirt that provides a sure seal. The Sea Vu is treated to resist fog so you never have to worry about a cloudy view. Note: This is a snorkel mask only. Not designed for diving. General Sizing: Measure the length of your face from chin to eye level. Choose the S/M size if the length is less than 4-1/2″. Choose the L/XL size if the length is greater than 4-1/2″.