Boss Office Products Black Contemporary Ergonomic Adjustable Height Task ChairKneeling stool offers excellent ergonomic support and ease of use Adjustable knee height allows for multiple users Ergonomic design eases the hip forward and encourages an upright posture by aligning the back, shoulders and neck to relieve strain on the lumbar muscles Black fabric seat and knee platform provides comfort for long periods of time Pneumatic gas lift seat height adjustment Hooded double wheel casters Black tubular steel frame Features