Both A & B grades are made from the same material, the only difference is that A grade is woven loosely (open weave, like mesh) and B grade is a tighter weave.
Grade C (Standard Sunbrella & In Stock Options) – Top quality cushions made with the best materials. Grade C cushions are typically made from synthetic polymers called acrylics, which are 100% solution dyed before they become a fiber for increased colorfastness.