Yaheetech Modern Office Chair Mesh Fabric Cushion Mid Back Computer Chair Lumbar Support Desk/Task Chair with Arms/Wheels Black HEAVY DUTY: This office chair is constructed of premium nylon mesh backrest, plastic armrest and metal; solid structure can satisfy your daily needs, durable and sturdy chair for your long-term use HEIGHT ADJUSTABLE: Features with a gas lift beneath the seat to adjust the height, easy adjustment to customize your desired chair height THOUGHTFUL-DESIGNED BACKREST: According to your different sitting position, the tilt angle of the backrest can be adjusted by a simply rotating the control knob under the seat; breathable backrest is made of high quality nylon mesh, which is good for heat dissipation in summer 360 SWIVEL CASTERS: 5PCS non-marking casters can be rotated in all directions, convenient for you to move the chair, fetch files/books, etc SIMPLE ASSEMBLY: All necessary tools and hardware are included, easy to assemble under the detailed instructions