5 legged chair base with nylon glides on legs, by Swivlon(R), is one of the highest quality and longest lasting swivels on today's market. The swivel is unique in that no steel balls that can rust or fall out are used. The swivels use high tech polymer rings that have a true 360 degree contact of the two surfaces of the bearing as they turn against each other. There is no steel against steel or nylon against steel movement. The chair swivel base has a flat pitch.