Smugdesk 6813A9 Ergonomic Office Chair, Large, Black ERGONOMIC BACKREST - Open mesh design creates a breathable, well-ventilated backrest. Ergomomic office chair backrest with lumbar support will help you keep in a right position during long time working. BREATHABLE PADDING SEAT - The padded mesh seat is thick and resilient. Made of high quality thick sponge and breathable mesh clothes, prevent body heat and keep your hip and legs sweat-free. MULTI-FUNCTION MECHANISM - Pneumatic controls make it easier to raise or lower the seat. The rocking mode can relax you from heavy work, pull out the handle to start rocking and pull it in to stop. This chair can support up to 250 lbs of weight SMOOTH AND DURABLE CASTERS - The PU casters provides great mobility , suitable for hard floor, carpet floor and more, without noisy when it swivels and won't scratch the ground. SATISFACTION GUARANTEE - We dedicate ourselves to bringing great sitting experience to all customers, you don't need other tools to install it. We offer you a 12- months warranty. So you can buy it at no risk.