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Install an eye lag screw or an eye bolt at the height you want to hang the sails. Install the hardware on other attachment points if you're using them. Attach the turnbuckles and snap hooks or carbines to the sail. Hook the corners on to the posts. Secure the last corner by stretching out the tension strap.
Use eye lag screws for wood or eye bolts for metal. Start by drilling into the post, using the same size drill bit as your eye lag screws or eye bolts. Screw the eye lags or bolts into place.  You'll likely need a ladder to reach where you want to install the hardware. Add a washer on the back if you're using eye bolts. If you're attaching it to your house, you'll need to add a fascia support bracket. The fascia is the band that runs right under your roof. A bracket helps reinforce the area so the shade doesn't put too much pressure on the fascia.  The bracket goes behind the fascia on the rafters in between the house and the fascia. It has a piece that goes through the fascia, which is where you will screw in an eye hook. Drill from the back of the fascia with a small drill bit, using the bracket as a guide. Drill from the front with a larger drill bit. Stick the screwing mechanism on the bracket through the fascia so it comes out the front. The bracket should be flat against the rafter on the other side. Drill through the rafter with a 0.5 in (1.3 cm) drill bit in 2 places, going through the holes on the bracket. Stick 0.5 in (1.3 cm) bolts through the holes, and secure them with washers on the other side. Screw in the eye hook on the front of the fascia. A turnbuckle is a device that lets you adjust tension. Use snap hooks or carbines to attach it to the corners of the sail.  The corners of the shade should have grommets or steel rings in place. Just attach the hook to the turnbuckle, and then slide it into place over the corner of the shade. For one corner, it's sometimes better to use a tension strap. This corner will be the last one you put on. A tension strap is just a stretchy piece that you'll use in place of the turnbuckle. You can find them at hardware stores, but one may also have come in your shade hardware kit. Slip the hooks on the other side of the turnbuckle into the eye attachments on the posts or your house. Leave 1 corner unhooked while you adjust the tension on the others.  Turn the turnbuckle to increase the tension on the attached corners. If you're having trouble attaching a corner because it's not long enough, you can add a couple of carabiner hooks to make it longer. The last corner should have a tension strap instead of a turnbuckle. That's because it will be harder to put it in place than other corners, due to the tension you've already created. Stretch the shade out, and hook it on the last eye attachment.