Mid-back chair frame features a mesh back that allows air to flow freely when you're seated to help you stay cool throughout the day. Lumbar support offers ergonomic support for your lower back to help prevent strain through extended seating. Ratchet back device allows you to adjust The back height to meet your specific requirements. Seat and back angle can adjust independently for maximum comfort. Chair frame also includes pneumatic seat-height adjustment, seat slider to adjust seat Depth, 360-degree swivel, tilt tension and more. Chair frame is designed for Loral Bonded leather seat cushions or fabric seat cushions, and arm brackets (each sold separately). Loral seat cushions come in four colors: Black, Gray, Navy and red.