[Solinoid]

I've had one for about 8 years and the rubber on the armrests has started to degrade in the past 2 years, but other than that no issues to report. Replacement armrests run about 60$.

That said I worked in an office that had about 200 of them, and chairs subject to heavier individuals had problems with the gas height adjuster failing. This was about 5 years ago so maybe they've sorted it out.