ERGONOMIC DESIGN: Having a chair with lumbar support is especially necessary for all-day working and studying. This ergonomic office chair will not only help to sit at correct sitting postures but also help relieve stress and reduce fatigue after long-time sitting. The curved backrest design line up with the human body's spine natural curve to provide low-back support. COMFORTABLE SEAT: Several detail designs to provide long-lasting comfort. Ergonomic armrest with suitable height to allow users to put hands on top to relax. High-density sponge seat with sufficient seat depth to reduce pressure on the user's hips. Breathable mesh back and seat allow airflow to help users stay cool during a long time studying. ADJUSTABLE HEIGHT: With adjustable seat height. Pneumatic controls make our office chair easier to raise or lower - simply pull up the lever and adjust the seat at your desired height. QUALITY MATERIAL: Product equipped with heavy-duty metal base and casters that can support up to 250 lbs. These 360-degree swivel caster wheels enable silent and smooth sliding while never scratch on your hardwood floor. EASY ASSEMBLY: Include a straightforward, 5-step installation instruction to help you quickly assemble this office chair. All necessary tools, hardware, and spare parts will be provided. We recommend not to tighten the screw until all screw lined up with the holes, and tight the screws firmly before using.