Boss Office Products B6338 Multi-Function Task Chair in Black Contemporary ergonomic mesh back designed to provide exceptional back support and to prevent body heat and moisture build-up Ratchet back with active lumbar support; Height and width adjustable arms 3 paddle multi-function tilting mechanism; Seat tilt lock allows the seat to lock throughout the tilt range Adjustable tilt tension control; Pneumatic gas lift seat height adjustment 27" nylon base; Hooded double wheel casters