Herman Miller Aeron Posturefit Stand Kit Chair, Plastic, Black, Size B (Medium)

This supports the back from the base of the spine, and doesn't feel as extreme as the lumbar support. That said, it does provide all the support needed and it is a nice adjustable upgrade for the Aeron. The previous "old" lumbar support only has two support settings, and to select between a little support and a lot, it requires removing the support bar from the chair, flipping it over, and reinstalling it. For the PostureFit, the adjustment can be made using a knob for a little support, a lot of support, and everything in between. The pieces fit on the frame in a way where the original designers apparently planned for this type of addition. There's a hidden bump/tab that helps align the bracket for the knob. Initially the bracket was a little tricky to get aligned, but it's because the pieces fit so tightly together. Fits on the Aeron in a way that makes it feel like it came this way from the factory. Despite what the manual says, the PostureFit kit can be installed with a Philips head screwdriver and nothing else. There are YouTube videos for help installing if you get stuck, but I feel that the written instructions are reasonably written and the illustrations are sufficient. The bottom of the support is pulled toward the front of the chair by a cable. This cable is held in place by a bracket, but most importantly, the cable passes straight through the mesh back rest. I do not think it is possible to install it without widening a small hole in the mesh back rest. I was very careful during the install, but there is still a small widened area of mesh where the cable passes through. This means that once you install the kit, even if you remove the kit, there will always be a small hole in the base of the mesh back rest. I double checked the location for mine, and it is so low on the back rest that it is below the seat bottom. This means it is only visible from behind the chair. If this sort of irreversible change bothers you, this kit may not be for you as replacement back rests can be very expensive. If you already have a lumbar support on the chair, I am not sure that this kit is worth the money. In the absence of lumbar support on the chair, this kit is absolutely worth the money.

Okay, so first the pros. This thing is insanely easy to install and takes maybe 10 minutes of modification to be up an running. Kudos for being consumer friendly on that front. My chair is an '07 and it installed with no issue. (P.S. I installed solely with a Philips screwdriver fyi). Second pro is this lumbar support does provide a more even support than the standard Herman Millar lumbar pad and for what it's worth... is an upgrade. HOWEVER, what you should know before buying is that this lumbar support sits VERY low on the back. I'm a fairly short person (5'5") and I would argue this support is a hair too low for me. However, if I keep it on medium support then I don't notice after about 15 minutes of work. I was hesitant to give this 4 stars as I can easily see this being a bigger problem for taller individuals who use size B Herman Miller's. BUT, my lumbar does feel more supported with this than without. So it does do it's job with the caveat of putting up with the sensation of something touching your lower lumbar. Short version-- this sits very low for a lumbar support but Herman Miller Aeron's are better with this support than without? So it's a weird catch 22.

I bought my first Aeron chair three months ago. Since it was paid for by my employer, I splurged and chose the posturefit option. The chair was great-- so great that a few weeks later I decided to order one for my home office. Herman Miller was having a sale, and I selected a fully loaded Aeron--but this time without posturefit, as I'd read reviews here that said the lumbar pad offered even better back support. In hindsight, foregoing posturefit on my second Aeron was a stupid decision, because (a) posturefit had worked well for me in the past and (b) the lumbar pad was just a solid block of rubber that was bound to be uncomfortable. And it was. The lumbar pad rendered the chair almost useless to me. So, I sucked it up, ordered the posturefit unit, and installed it myself. The installation is not trivially easy, but requires no special skills (only patience). As others have noted, forcing a wire through the mesh in the seat back feels wrong, but it's no big deal. Still, I wish I had just ordered the thing with posturefit to begin with. I would have saved 70 bucks. In the meantime, anybody want to buy a mint condition lumbar pad? :-)

This works OK. It's not as high up as the regular lumbar support pad can go but high enough. I wish I could just keep using the original support pad but I already replaced it twice and it just keeps popping out. This will work for the time being but I probably just need a whole new chair (the remastered's lumbar which looks way higher and more reliable), then I'll keep this as a backup or for friends or whatever. Really disappointed I couldn't get what I wanted out of the classic but it is a 10 year old chair so I don't know what I was expecting "cheaping" out. If you can call $350 cheaping out (500 with all the lumbar pads I bought). I did find a little hack by placing the original lumbar pad onto the top of the Y bracket of the posturefit but I expect this will be too much support for many. I actually find it perfect for me. Using this method the posturefit works more as a holder for the original lumbar pad rather than a back support itself. I wish they had just designed the posturefit to go higher up for a full back support, seems like a fatal design flaw. I realize this is also meant to support the sacrial region but you can support the sacrial region and lower-mid area too. Kill two birds with one stone.

I've got a fully loaded Aeron that I bought used in 2020 and it came with the sliding adjustable arch support. I'm a taller guy and I could not find a comfortable position for that thing so I ended up removing it. I wanted to try this one out and it's really nice. I had to pull up a video to see how to install it but after that it was fairly easy.