AppleRound Air Stability Wobble Cushion, Sliver Grey, 35cm/14in Diameter, Balance Disc, Pump Included 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 easy inflation. Cushion is delivered deflated. No instructional DVD. Presented in a nice COLOR box. Durable & safe: 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, just insert the pin without the barrel of the pump. Find the valve in the cushion on the 4th outer ring--one spiky dimple is replaced by the valve inside of a small hole. 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. Seller is ready to provide hassle-free after-sales service and usually replies most emails in 12 hours.