The Gaiam Balance Disc Wobble Cushion is designed to turn any chair or seat into an active one by adding instability, which helps to strengthen your core and improve posture. This 16-inch diameter inflatable cushion is great for use on office desk chairs, as a meditation seat, or as an alternative seating option for active kids. It arrives partially inflated and includes an inflation needle to adjust firmness to your preference. The cushion is versatile and can be used for various strength and balance exercises, both in and out of a chair.