This office chair comes with an certified safe-to-use gas lift to meet the needs of people of different heights. It also supports rocking motion tilt, the reclining function of 90-105 which allows you to relax yourselves. This ergonomic desk mesh chair is built with flexible armrests (can be folded up 90), which means when you dont want to use them, you can flip the arms up and put the chair under the desk for saving space.The seat with high-density thick foam which has good elasticity that is difficult to deform to keep comfortable for long hours.