2 x Cork Yoga Block Set Natural Exercise Brick Support for Balance, Stretching and Stability2 x Cork Yoga Block Set Natural Exercise Brick Support for Balance, Stretching and Stability Training your balance for yoga, ballet, or another sport? This sturdy cork yoga block from Randy Travis Machinery is just what you need for your next workout. In 100% natural cork, this exercise brick will stay put with its non slip surface. Smooth, rounded edges provide comfort underfoot. No worries about toxic chemicals, either. Sourced from renewable cork