You must remember, this material is waterproof and must be installed at a slant with the point of the triangle upwards. If they are installed flat, as I mistakenly did, they accumulate a lot of water and sag - even pulling the polls they are anchored to use at least 2 bags of concrete per 4x4 poll.  I am using the 2 waterproof ones at a slant over my greenhouse and I ordered the mesh type super ring wind sail for my deck.  Using the same polls and order 1 installation kit per sail- saves a lot if time too. I do love my wind sails. The picture above of the one between the trees is the mesh type and still hangs there with even a hard rain, that never has an accumulation of water. They are beautiful and add grace and color to any deck or garden area. Good Luck.