Seat plate mechanism with one lever , Paddle A is for seat height adjustment. It's seat initialized angle is 3°，Knob B is for the movement of B347G, the maximum travel range is 47mm, Knob C is for the back angle adjustment, the back angle is in the range of 78°～103°; Knob D is for the back bar up&down adjustment, the adjusting range is 0～60MM, R411 can rotate in a certain range.