Measurement of shade sail is from D ring to D ring, edges are made slightly curved to prevent middle from sagging for best appearance and performance. Shade sail should be approx at least 0.5 ft to 1 ft shorter than the distance between actual mounting points without any cable extension, additional installation hardware kits may be required to create mounting points and tension.Fabric material is permeable, allow water and airflow to go through to prevent pooling water.95% UV blockage, significantly reduce harmful UV ray and temperature, allowing a constant circulation of fresh air, perfect for garden patio outdoor party.Sun shade sail is finished heavy duty webbing inside the seamed edges, corners are finished with stainless steel D ring for easy installation.Warranty: Shade sail comes with 3 years warranty under normal weather condition, your 100% satisfaction is our goal. We recommend to buy with our hardware to maximize the performance and appearance. Why are we so confident? Because we are the manufacturer.