Simple, at its simplest, it is a swivel-only, fixed height, conference chair with fixed arms. Choose pneumatic height adjustment and adjustable arms, and it is a desk chair. With the optional Knee-Tilt mechanism and adjustable arms(upcharges apply), it becomes a fully ergonomic task chair. The elastic knit mesh back is engineered to provide lumbar support. The seat is always upholstered, and the back can also be upholstered, if desired.