Gaiam Balance Disc Wobble Cushion Stability Core Trainer for Home or Office Desk Chair & Kids Alternative Classroom Sensory Wiggle Seat TURN ANY CHAIR INTO AN ACTIVE SEAT: Place the disc on top of any chair or seat to add instability to strengthen your core while improving posture and sitting comfortably VERSATILE CUSHION: Use balance disc with a variety of strength and balance exercises, in or out of a chair, to increase core strength and balance AIR CUSHIONED SEAT ANYWHERE: Works outdoors for a quick seat or on hardwood and carpet flooring and also makes a great meditation seat or wherever you need a little extra cushion ALTERNATIVE SEAT FOR 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 DIMENSIONS: Measures 16 inch diameter