Chair parts,chair accessory,chair mechanism Features: 1) Pneumatic height adjustment 2) Tension adjustment knob 3) Synchro-tilting 4) Permanent contact in locked position 5) Locking procedures: a) Find the desired position b) Push the left lever downwards 6) Unlocking procedures: a) Push the left lever upwards b) Give the pressure to the backrest 7) Applications: executive chair, senior executive chair and multifunctional chair