The Wiggle Wobble Chair Feet transform a standard school chair into a Wobble Chair, enabling kids to have an outlet for excess energy while working, alleviating anxiety, hyperactivity, and boredom. No tools required for simple installation: each foot snaps right onto the standard round school chair glide (measuring between 1.12" and 1.25" in diameter). Can be used on tile, wood, and carpeted floors. 2.6" H x 3.8" diameter. Safety tested.