No need for Air Vents, with Samm's Umbrella     ENGINEERED WITH YOUR PROTECTION IN MIND “DON’T BUY ANOTHER THROW AWAY” Engineering Ingenuity   High Strength Fabrics 190 Threads/SQ. IN.   Beverage Cap Design - 21 Tips   Rust Resistant Zinc Plated and Aluminum Ribs   Supported Edge   Does NOT Trap Wind   Sheds Water Despite It’s Shape   Designed by Dimension THE BOTTLECAP DESIGN IS FAR SUPERIOR IN WIND THAN THE CONVENTIONAL (DOMED) UMBRELLA   The effective protection of an umbrella is it’s diameter.