High-back Mesh Chair features flexible, breathable mesh support from seat, lumbar segment, back panel to headrest. With complete mesh over the durable plastic frame, air will flow freely to help keep you cool while you work. Adjustable lumbar support offers ergonomic support for your lower back to help prevent strain through extended seating. Headrest angle adjusts for optimal positioning. Nylon arms padded with cushioning polyurethane adjust in height from 24-1/4" to 28-1/8". Easily adjust comfort functions with the Simply Synchronized Mechanism for seat-height adjustment from 18-1/8" to 21-7/8", tilt & tilt lock. Other functions include 360-degree swivel & tilt tension adjustment. Nylon, five-star base is equipped with dual-wheel casters for easy rolling from task to task. Seat measures 20-1/2" wide x 18-1/8" deep. Back size from lumbar support to headrest is 19-5/8" wide x 21-5/8" deep.