You can fill the bottom tube with water to keep the net in place.
Brad's Deals Editor Julie,
This Pure Garden Patio Umbrella Net, already on sale for $26.99, drops to $24.99 at Tanga when you use our exclusive promo code BRADSDEALS during checkout. Plus shipping is free, making this the lowest price anywhere by $5. This zip-up encasing can fit umbrellas up to 7.5' in diameter. You can fill the bottom tube with water to keep the net in place. Sales tax is charged in most states.