I ordered 2 triangles (lime green and turquoise) and thought we could overlap them to make a square but no matter how and where you set your posts, it's not going to be square. We used the to cover our large patio so our furniture would not get so faded as the sun comes around to that side of the house after 12 pm and stays until dark. Living on a mounatin, we get some heavy winds and lost 4 big umbrellas last year. After reading other reviews, I thought this would be worth trying. This summer we had winds that exceeded 80 m.p.h. and while these winds took down and uprooted 150 year old oak trees, these sun sails held strong throughout the whole ordeal. These heavey winds are not normal for this area but it's happened 4 times already and the sun sails are still hanging. They do need to be tightened as they are sagging a little now from all the winds and rain.
One thing we are going to change is the way they are hung. My husband planted 2 - 12' posts, 3' in the ground, topped off with cement and covered them with a heavy white plastic, square insert (made for fencing, capped it and bolted larger eye hooks at the top side of the posts. The other eye hooks come off the posts on our outdoor kitchen (that part of the bar has a roof and 20' wooden bar top) Since the 2 triangle sails didn't work, I ordered a square one. The sail comes under the roof line above the bar top and keeps the rain off the bar stools. The sail angles down a little from the other posts to allow water to run off. (Don't know what they are called but the "T" shaped things that you tie a boat off on a dock is what we are looking to use to replace the screwed in eye hooks.) This would make it so much easier when the sun sail needs to be tightened. The way it is now, is just too much trouble to deal with. We did replace the ropes they sent with a little larger ones simpley because of the constant winds blowing up this mountain but if you don;t have that problem, the sent ropes would work just fine. Since we now have 3 sun sails (2 triangles and 1 square) we put the large, square turquoise first and added the lime green to the top side and it blocks out more harsh sunlight. They do give shade but the mesh keeps you cooler. Just wish they were waterproof. They do drip rain when it comes down. But it has saved our cushions from getting faded and held up through heavy winds - I'm impressed with these sun sails.