Yoga blocks are made of foam, wood, or cork. They can be turned to stand at three different heights, making them very adaptable. If you plan to do a lot of swivel at home it's worth it to get a set of blocks (helpful for poses where both hands are reaching toward the ground). If you're going to attend classes, blocks will be provided for you.http://www.prior-fitness.com/a....erial-yoga-accessori