Headrest does not adjust up or down sitting in the chair the headrest pushed in on my shoulders I'm 6'3". I ended up leaving it off. Noted on the instructions it's listed as an 'optional' piece. Not a big deal overall. There seat cushion just the stretched flexible mesh. After a few hours of comfortable sitting I find it begins to feel a bit tight in the hamstring I'm 185 lbs. I'm a little concerned that the material will stretch overtime. The lumbar support raises but during use (leaning back at times) it clicks down the notches until its a the bottom again. In short seems like it'd be a good chair for an average sized fellow. If you're taller I wouldn't recommend it.
With the shift to work at home I needed a desk chair that did not make my back hurt after an hour or two. I visited a store and was ready to buy a different model but it wasn't in stock. So I went to a store that had the model I was interested in but the manager recommended I try this one. I decided to grab it as it felt good and had the neck and lumbar support I know I need. One week in it has done the job. As long as I remember to get up and walk around the house (I do that a lot i the office) I'm doing fine and even if I don't get up and move around the aches are minor I am not a mechanically inclined person and assembly instructions often give me fits. I can say that while it took me a bit longer than I had hoped I did manage to assemble the chair without any fits of anger and rage. i would recommend this chair.