[Ergonomic Design] The SIHOO ergonomic chair possesses all of the characteristics of an ergonomic design. The S-shaped backrest design mimics the human spine and fully supports the back. The ergonomic office chair can easily tilt 110°–116°–126° and is height adjustable by 10 cm in order to help you find a comfortable position after long gaming sessions or when working [3D Armrest] Unlike 2D armrests, 3D armrests can be raised and lowered in 5 positions, and the PU leather armrest surface can also be adjusted back and forth and rotated left and right as your sitting position changes, providing multi-angle support for your hands so that you can maintain a healthy, comfortable posture when gaming, streaming, working, or napping. [Mesh Material] The springy foam at the front end of the seat cushion and its curved design give you plenty of support while sitting. The seat and backrest are made of polyester mesh which is tough and breathable and provides support while keeping you cool and sweat-free on hot summer days. [High Quality & Easy Assembly] Every part of this computer office chair has undergone strict safety and quality testing, including cushion impact tests, armrest fatigue tests, and chair foot static pressure tests. The gas lift of this high-back office chair is BIFMA and SGS certified, and it can bear up to 330 lbs (23.57 st) of weight. The simple instructions allow anyone to assemble the ergonomic executive swivel chair in just 7 easy steps. Free returns and refunds within 30 days if the SIHOO office chair is faulty or if there are any other quality-related issues.