Find your best position using the multiple height, tilt, and lift settings, and use the tilt lock function to stay in place. Continuously height adjustable with the gas pressure spring and flexible backrest angles provide completely customizable comfort. Height of seat surface: 41-49cm. Power supply of the massage function: USB(5V).Please open the packaging carefully to avoid sharp objects scratching the chair. We will offer assistance and a satisfactory solution to you in a timely manner.