Almost everyone in the world would not be comfortable for long sitting on a hard chair. Are you include that so? If yes, then buy a high back patio chair cushions is a must to do. Not only for indoor, outdoor high back chairs would be comfy and inviting when paired with cushions. Cotton canvas, acrylic linen, Dacron/PET and PVC are the popular cushions materials for patios. The latter three are water and UV resistance so that they are the best choices for the outdoor goal.