Does my Herman Miller Aeron Classic Chair have a Side-Activated or Top-Activated Gas Lift?

99% of generic office chairs have a top-activated button. That means your chair’s gas cylinder has a button on the top which is pressed by either a mechanical lever or a lever activated by a wire.

However, this can get mighty confusing with some products such as Herman Miller’s Aeron chair.

Why knowing the model of your Aeron is not so cut and dried

Plenty of older Aeron Classics have been serviced, repaired, or refurbished over the years, and many have had their mechanisms swapped during that process. This creates confusion — especially for chairs supplied around 2013, when Herman Miller stopped producing the Classic with a side‑activated gas lift. Around that time, some distributors labelled chairs as “2013” based on the supply date, even though the actual manufacturing date was 2012. To complicate things further, Herman Miller produced the Aeron Classic with both gas‑lift styles in the years leading up to 2013, so a chair’s age doesn’t always guarantee which gas lift it originally shipped with.

So how can you be sure which gas lift you have on your Herman Miller chair without removing the entire gas lift?

The only reliable way to identify the mechanism is to remove the plastic cover directly under the seat and visually inspect it. This two‑piece cover opens easily from the front using a plastic wedge — a narrow plastic paint scraper works best and avoids damage.

Tip: When I’m doing this job, I usually remove the two large Hip Bolts so I can lift the seat and service the mechanism at the same time. Hip Bolts are notoriously difficult to remove, so leave them in place if you don’t have the right tools — you’ll still get a clear view of the mechanism’s inner workings once the cover is off.

Now what?

Once you have opened the mechanism cover, take a look at the where the gas lift fits into the mechanism, then operate the gas lift button as if you were adjusting the height of your chair. You’ll see either of these two things shown in the videos below: