our company have manufactured office Chair with US Pantent-US PATENT NO 6,8505,405 B2 OCT 19 2004). We supplyed our product to Samsung Company and LG company. our product is that LSU(lumber support unit) include a lumber plate attached to a lower portion of a tiltablw backrest part and the elastic plate is project in aa circle so that it propos up and stimulate ergonomically the lumber vertebra. We can support all service related to LSU.