This type of sail shade is connected from the corners to poles or structures. There is a stainless steel cable inside a pocket sewn to the boundary of the sail which connects to turnbuckles on two or more corners. Turnbuckles connect to eyelets on the posts or structure and closing them tensions the cables and the sail into a taut shade with concave edges. The corners can be at the same height or different heights to create a 3D shape for enhanced wind resistance and rain drainage.