This highback mesh ergonomic chair has been designed to provide a superior level of comfort. Specifically intended for users who are in their chair for five or more hours per day, the Ergohuman chair features exclusive flex zones that ensure constant back and lumbar support. With a wide range of ergonomic adjustments, this chair can be easily customized to fit virtually any user. Instant lift seat adjustment is controlled by a lever located beneath the right front of the seatpan, and positions seat height from 17'' to 21''. The mesh backrest is adjustable in both height and angle. To adjust back height, simply reach behind chair and pull the chrome buttons, then lift backrest to desired location. Synchrotilt seat mechanism with adjustable tension control allows back angle to adjust freely, and it can be locked into three different positions. To help the Ergohuman accommodate users of different heights, the depth of the seat pan can be adjusted. Simply pull back on lever below lower rear of right side of seat to release seat depth lock, and the seat can slide freely forward and back.Adjustable armrests help you keep your elbows at the proper 90 degree position while providing additional comfort and support. Height can be adjusted by pressing button on side of arm and lifting arm into any of ten different positions. Angle of armrests can be pivoted into three different positions with a total range of 16 degrees. Chair is made from 97 recyclable parts. Ships ready to assemble.This chair has been Greenguard cerified to support better indoor air quality for businesses and home offices.