LyShade 16'5 x 16'5 Square Sun Shade Sail Canopy with Stainless Steel Hardware Kit (Sand) - UV Block for Patio and Outdoor Long-lasting, knitted polyethylene allows rain to pass through so water will not collect or pool Advanced engineered fabric prevents 90-95% of harmful UV rays though it is breathable allowing air to circulate Reinforced, stitched corners with steel fittings attach quick and easy to mounting points Easy to attach and take down in a few minutes