Silhoflex rib-less smooth back modern design with ergonomic shell that incorporates a built in lumbar support. Shell passes CAL 133 testing with no additives. Frame made of 11ga. cold-rolled steel with exclusive Columbia 360 brazed on foot extensions. Available with various glide options such as TPR, ARMOR, FELT and STEEL tat makes the chair suitable for any surface. Available in 14, 16 and 18" heights.