U-shaped cushions have a cutout to relieve pressure on your tailbone. Because their cutout is at the back, U-shaped cushions help you keep your spine in a more natural position than doughnut cushions.
Gel Padding—Cushions with gel padding feel firmer than those with foam. They also stay cool under your legs.
Wedge Profile—Wedge cushions prop you up at a slight angle, which promotes blood flow to your legs and helps you sit up straighter.