Mid-back task chair with posture lock features deeply contoured foam that supports the body for all-day comfort. Control options encourage good posture. Curvilinear back has pronounced lumbar support. Other features include an integral headrest, shoulder-height recess to cradle upper spine, wave-formed seat to provide a natural "settling in" place, fully upholstered outer back and five-star base with hooded dual-wheel casters. Functions include pneumatic seat-height adjustment from 16-3/4" to 20-3/4", back-height adjustment, 360-degree swivel, tilt, tilt tension, tilt lock and posture mechanism/lock. Arms adjust in height and width. Super-soft arm pads offer maximum seating comfort. Distance between arms is 18-5/8" to 21-5/8". Seat measures 21-1/2" wide x 18" deep. Back dimensions are 19-3/4" wide x 23-1/4" high. Mid-back chair is certified by SCS to be in compliance with specific, indoor, air-quality emission requirements and meets or exceeds applicable ANSI/BIFMA standards.