AppleRound Air Stability Wobble Cushion with Pump, 34cm/13.5in Diameter, Balance Disc, Sensory Wiggle Seat 13.5in/34cm in diameter, large spiky dimples on one side (for standing), very small dimples on the reverse side (for sitting). It helps promote core stability, also a wiggle seat provides sensory input for kids. One 6-inch hand pump included for easy inflation. Cushion is delivered deflated. No instructional DVD. Presented in a nice COLOR box. Durable & safe: Lab tested, contains no banned phthalates and heavy metal elements in the US. Helps improve balance, coordination and flexibility; Good for active sitting, muscle strengthening, and joint stabilization. Instruction: To inflate,the pin from the pump must break through the valve to reach inside of the cushion,or the pin hole would be BLOCKED by the valve wall preventing air to enter. To release the air from the cushion,insert pin without the pump barrel. Seller Warranty: Should pump be faulty or cushion defective, please Contact Seller directly (other than Amazon Customer Service) from Amazon Buyer Central against your order for a replacement or refund. 14in/35cm in diameter, large spiky dimples on one side (for standing), very small dimples on the reverse side (for sitting). Free 6-inch hand pump included, for users to adjust air pressure to desired firmness. No instructional DVD. Presented in a nice COLOR box and ideal as a gift. Lab tested, this product fully complies with EU &amp; US Safety Standards. It contains no US banned phthalates and heavy metal elements. Safe to use! This wobble cushion or stability cushion is an ideal tool for improving balance and posture, Coordination and Flexibility. It is good for active sitting, muscle strengthening, joint stabilization. The cushion also serves as a good Wiggle Seat for kids. It becomes popular with teachers and parents alike to calm the hyperactive child. Many parents have found wiggle seats to be a life saver during dinner and homework time. While teachers love them for the calming effect they can have on children, many even report improved behavior for ADHD and autistic children. Penetrate the needle of the pump through the valve for inflation, and penetrate the needle only without the barrel of the pump for deflation. Find the valve in the cushion on the 4th outer ring--one spiky dimple is replaced by the valve inside of a small hole. Please make sure the pin going deep enough to reach inner part of the cushion, or the air flow would be blocked by the valve wall, but not too deep to puncture the other side of the cushion. Q: When I insert the pin into the cushion and try to pump, no air enters the cushion. It feels like the air is being resisted from going in. The pump seems to work fine. A: The inserted white plug (air stopper) in the ball must be removed first! Inflation Instruction: To inflate, the pin from the pump must break through the valve to reach inside of the cushion, or the pin hole would be <span class="a-text-bold">BLOCKED </span>by the wall of the valve preventing air to enter. To release the air from the cushion, just insert the pin without the barrel of the pump. Then press the cushion, the air will come out from the needle top. Please penetrate the pin through the valve with care, deep enough to reach inside of the cushion, but not too deep to puncture the other side of the cushion.