In a retaining piece interposed between the adjacent rolling balls, a concave surface of each of both side surfaces of the retaining piece where it contacts with the spherical surfaces of the balls is configured to partly contact with the spherical surface of the ball. The assembly includes an access cover, and an access tube including a first opening, a second opening, and a substantially hollow body extending therebetween. The end-capped liquid crystal oligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The occupant support also includes a control unit 44 having user inputs configured to be engaged by a user.