THE PERFECT MATCH. BARE's DUO B twin lens design mask features a soft and supple double-flanged silicone skirt that provides a leak-proof seal and also incorporates a patented push-button buckle for lightening-quick strap adjustments. Paired with our low profile, low drag SEMI-DRY snorkel that uses a splash-proof guard that virtually eliminates water intake, the DUO B and SEMI-DRY are a perfect combination.