The height adjustable backrest provides support to the lower back for good posture and prevents back strain.		M1 Two level independent mechanism for height adjustment and back rake movement.		M3Three levels independent mechanism for height adjustment and back rake movement and seat rake movement.
M1 and M3 Seat height adjustment with high quality pneumatic gaslift.		Optional Armrest 98A - Height adjustable armrest. 9A - Fixed armrest. The height adjustable armrests made of high quality PP provide good support to the arms and shoulders. An option for 9A fixed armrest is available.		The NB4/NB5 chair base is made of strong reinforced nylon with R1 heavy duty nylon castors made for durability and ease or movement on carpet flooring.
R5 Durable Glider for Sturdy Support (Optional).