Curved edges : this shade sail has curved edges on each side , which allows pulling tightly and prevent sagging in middle. Material: Made of Virgin None Recycle 190 GSM HDPE (High-density polyethylene), material is breathable, allows water go through , block up to 95% UV harm. Durable: double layer webbing go through all the edges , no just on the corners, makes the shade sail strong and last long. Installation: our sun shade sail comes with D ring on each corner, easily install with our hardware ( sold separately). Customization: we make custom sizes, please contact us to place custom size orders.