A chair is mounted on ball-casters. Each leg of the chair is mounted on a caster wheel that is surrounded by a ring of small metal balls, such as ball bearings, enabling the chair to roll freely without scuffing or scratching the floor or dulling the floor polish, and making it virtually impossible for the occupant to lean back in the chair with any stability.
Chair with ball-casters
2015-12-15
Patent
Electronic Resource
English