Engineered to ergonomically support you as you shift and move, without the use of complex manual adjustments, this mid-back task chair features innovative Purpose technology for a personal fit. Three distinct flex zones support your movements and range of postures. The first zone fine-tunes the backrest to the curve of your spine to deliver constant lumbar support. second zone calibrates the back angle during recline. and third evenly distributes pressure points to enhance comfort. These zones control the movement of the independent seat and back and deliver continuous support. Purpose is designed to accommodate everyone from the 5th to the 95th percentile, making it an ideal choice for most people. Upholstered seat and back cushion are designed to contour to the body to offer additional comfort. Functions also include pneumatic seat-height adjustment and 360-degree swivel and adjustable-height arms. 25-1/2" diameter, five-star plastic base is equipped with dual-wheeled hard casters..