AGM Group AeroMat Balance Disc Cushion RedInflated cushion with both pebbled and spiky surface, adds instability and stimulation into workouts Use as a balance training cushion by placing it under hands, feet or lower back for challenging exercises; can be used for active ergonomic sitting by placing it on top of your chair Adjust the inflation level with needle for more challenging exercises Made with soft and pliable PVC, free of latex, inflates with 2 Way Hand Pump (sold separately) 13. 5"