Backrest Tilt Angle Adjustment Pull the single rod control lever completely backward and lean against back until a desired angle is achieved,and then return the lever to the original middle position to lock at an ideal angle.There are 4 positions with 25º range. The proper backrest angle can reduce the pressure on the spine. Backrest Quick or Slight Tilt Tension Adjustment Pull the lever outwards,open the tilt tension adjustment handle, and turn it forward or backward into a desired tension for quick tilt tension adjustment or close the handle and turn it forward or backward for slight tilt tension adjustment,and then close the handle and push the lever inwards to the original position to fix it. The synchro mechanism is ergonomically designed to enhance comfort and reduce strain.The back-to-seat adjustment/tilt is 3:1 ratio. Backrest Height Adjustment Lumbar Support Height Adjustment While sitting and leaning against the backrest,pressing the backrest height lever can change the height of backrest. A.The height of lumbar support can also be adjusted by pressing the backrest height lever.There are 4 positions locking and theadjustable distance is 2.36". B.Suitable height of the lumbar support would bring more comfort for one's waist. Seat Height Adjustment Pull up the single rod control lever and hold it while raising or lowering the seat to change the seat height.When the lever is released,the seat height is locked. Since a incorrect seat height contributes to back's fatigue,it is recommended that the angle of knees is slightly less than 90º and feet are level with the floor. Seat Depth Adjustment Push the single rod control lever forward to adjust the seat depth (The approximate range is 1.97"). When the pull is released,the position will be fixed. Ideal depth is achieved when the upper legs are on the seat,the lumbar area is in touch with the backrest of the chair,and the back of knees does not touch the edge of seat cushion. Armrest Height Adjustment Press the two-side armrest height adjustment buttons to raise or lower the armrests.There are 8 positions with 3.15" range. Recommended armrest position: Allow arms to rest comfortably on the armrest at a 90º angle while the armrest is 1" higher than the elbow. Arm Pad Angle Adjustment Arm pad angle adjustment:a range of 9ºcan be achieved by swiveling the arm pads inwards. The best angle could be reached when the arms can rest naturally on the arms pads while working. Arm Pad Forward and Backward Adjustment Forward and backward adjustment: push the arm pads forward or backward to a desired position. The range for it is about 1.57".