New Open Box item...does not come in original packaging * Place the disc on top of almost any chair or seat to add instability to strengthen your core while improving posture and sitting comfortably - great for office desk chairs. Can also be used without a chair * Shape : Round * Works great as meditation seat or wherever you need a little extra cushion - also effective as a 'chill chair' for young children and active kids * Great for classroom aged children at home or in the classroom as an outlet for hyper or ADHD kids allowing them to release excess energy while staying engaged and focused longer * Measures 16 inch diameter / Includes Inflation Needle to inflate or deflate for cushion preference / Air pump not included