With the same uncompromising qualities in design, craftsmanship and performance as the classic Cerra collection, Cerra XT also features a heavy-duty synchro knee-tilt mechanism, generous seat and back proportions and a reinforced frame that accommodates up to 500 pounds. 883-H-XT High back task chair features heavy-duty synchro knee-tilt mechanism, concealed back height adjustment, tension control, black adjustable t-arms and steel reinforced black aluminum base.