Balance Balls are a classic desk toy. Also known as Newton\'s Cradle, the clacking of the steel balls will keep you entertained throughout the day. Pull back one or more of the balls, release them and the same number of balls will swing up on the opposite side. This set of balance balls is fun for the office and makes a great desktop gift. The apparatus usually consists of an odd number of identical steel balls each suspended by a bifilar suspension from a sturdy frame.