Alterseat has some major quality and ergonomic issues.

1. The preset recline is not linear. It's like sit straight, then a small recline level, then suddenly a huge recline.
2. The height adjustment lever is hard to control.
3.The armrest bottom mechanism got oil/grease leaking out. If you grip the armrest's bottom fully, sometimes you may get greasy finger.
4. This may be me, but the neck position is out for me. Ikea and Secretlab has neck support that match me.

They are good in their marketing blitz though, which is why I bought it. Maybe they even scrub the reviews cause hardly see any bad review.

Despite this, their cushion quality (density and comfort) is way ahead of Ikea Markus.

User Alterseat DT330.... not that great. The cushion is good and supportive but the back support is just meh and overall built quality is medium at best