Features: Adjustable air cushion " " Allows controlled dynamic sitting due to its square shape" " Well suited for starting back training or therapy" " Strengthens torso muscles " " Keeps the vertebrae gently in motion Trains spinal musculature Can help maintain an upright position Exercise poster included (all exercises of the product group “Dynair Ball Cushion” are applicable. Exercises only vary in intensity based on the chosen type of ball cushion)