These were great for protecting the fabric cushions we have from the sun, and they never blew away because the elastic on the bottom edge was snug. 
When it rained though, the water absorbed through. I was disappointing and didn't want my fabric or pads ruined by water.
I had six chairs and had six covers. Now I have no covers and six pads all stacked up on two chairs under a tarp when it rains. 

Pros: sun proof, wind proof, easy front handle to help with eay removal.
Cons: not water proof. Even with light rain sprinkles the moisture went through.