21' x 21' x 21' Triangle Sun Shade Sail - UV Protection Outdoor Canopy Cover for Backyard, Porch, Pergola, Deck, Garden & Patio - Perfect for Shading Outdoor Living Spaces (Green)

These are the third or fourth replacements. Couple different suppliers - these windscreens4less are in line with the better ones - D rings not rusting, double looped. (prosource Nov 2015 was a single loop). Good for two or three seasons, maybe four depending where you are i guess, winter storage, and how many cats decide they are hammocks. very cute ... until they fall thru an old one, no rip stop material here. Spare one handy. shade that is.Original plan was three 16x16x16 triangle shades out to steel posts placed away from the house in a way to maximise the shade sail coverage while keeping the posts to three, outside of the deck. Two more sails have since been added once the angles were figured and another anchor point added to the house. Triangles bow inward under tension, so the overlapping shades give fuller coverage, even double shade is nice in a few places, and keep it more interesting, especially if you can figure alternating tie off heights. square is just square.Noteworthy Extra Hardware used:3/16" Dacron rope. DavisRopeAndCable dot comStainless Turnbuckles. Sailrite dot comshades replaced, hardware holding strong.all the shade brands seem to provide the same basic white rope for tie offs where direct D ring to metal connectors cannot be made to the anchors. for a quick temporary placement the rope is ok - it is soft and easy to work with ... but will stretch and the shades will flap, shortening their life. if you look closely at the large shade installations at resorts or parks, they use steel cable under high tension. they even have the cable run through all the sides of the shades for extra tension. high quality shades too most likely. thousand$. didn't want fuss with steel cable initially, and ended up never seeing the need.The cheapest closest easiest to work with alternative i could find is Dacron (high strength polyester made by DuPont). US made rope. about 15c per foot for 3/16". it is very low stretch black rope. holds knots well. UV and weathers well. stephen davis at davis rope and cable assembly supplies tower rigging companies, but worked with my little order and walked thru explaining the rope on the phone. order was delayed due to staffing and sickness, extra rope length was thrown in. just because. can't beat that. that was 2017. 2021 I'm about to use him again for zip line rope and car port elevator winching lines.whatever tightness you can get the shades to with the rope, the better ... i've used the cheap white rope as a come-along, several loops back and fro the D ring and anchor, even pulleys, just for fun. whatever, the final tension on the Dacron is best/easiest done with a turnbuckle between the rope and anchor. there are plenty turnbuckles for sale here on amazon ... but mostly galvanised that will rust/seize pretty quickly. found a few stainless ones for $70 or so. each. eek. hence the mention above. around $15 or so, for a strong closed end stainless turnbuckle, with locking nuts. over time a new shade will stretch some; the turnbuckle allows additional tension to pick up the slack - so long as you got enough tension initially with the rope, allowing use of the full turnbuckle length later to pick up slack rather than re tying the rope.hope this helps someone do a shade install a little more robustly - no floppy sails!