I love these cushions.  They are thick and comfortable and fit our chairs perfectly.  I was kind of surprised they didn’t have ties, but I think I prefer that.  They are heavy enough and fit the chairs so well I don’t think they will blow away.  I would not hesitate to buy these again for other chairs we have.
Update  We had a pouring rain last night and were able to sit on the cushions today.  We can’t do that with the other cushions we have.