Underside of shell is ribbed for extra strength and stability. Front waterfall lip gives comfortable thigh support. Designed to promote correct sitting posture. Patented V-Back design provides ventilation. Concealed rivets attach shell to frame. Cushioned leveling glides reduce noise. Plastic colors of Red, Yellow, Green, Blue, Berry, Teal or Purple with matching metal frames. This chair is sold individually. All chairs ordered in quanties less than 6, same color, same size, may be subject to a broken carton fee. Ships F.O.B. Factory.