Herman MillerAeron 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.

Much better than a lumbar support, this actually works to put your lower back into the correct position. High quality device and fits perfectly with chair. Much better than the lumbar support option, as it provides better posture and the fittings are solid and sturdy (the lumbar support's fitment is prone to tearing at the connection between the foam body and the anchors for attaching to the chair).One minor gripe is that the installation instructions are not well done, with small pictures that do not show enough detail to determine the direction of objects pictured and the text is often ambiguous. Installation is not hard, but made more difficult due to these issues with the instructions. Took about 10 minutes to install, would have taken 2-3 with good, clear, instructions.

Adjustable support took a little time to install, but instructions were good (despite some poor choices in picture size and angle) and it went fine first try. The support is truly lumbar, and can't be adjusted for height, as opposed to the original foam crosspiece lumbar support. However, this support's single adjustment, which primarily affects how deep the support presses, affects where it hits the back vertically a little and so it's not hard to find a comfortable setting. With that said, it is much more comfortable than the old foam crosspiece and shouldn't break down like the foam does.

Everything is fine. Good value for money. I am happy with this purchase. Fits any *classic* Aeron. Posture fit doesn't hurt mesh of you chair! So don't worry.But keep in mind it's not very easy to install. Possibly before you need to watch some videos or/and read included instruction. It can take 1 or more hours.

The product feels solidly-built but it simply does not serve the intended purpose. I am not the only review to say this, but I did not read that review before buying. I am 6-ft 1-in. but that shouldn't matter much as the support seems too low for anyone including my 5-ft 4-in. spouse.The support is very low as pictured, giving the most pressure at 3" above the bottom of the seat (right at my tailbone - useless), then gradually reducing and ending at 7" above seat. This taper in support is because the wire connected to the hand-tighten crank pulls the bottom of the brace toward the seat, but the top is not supported and is easily pushed with the back.Save money and get better located and more adjustable support with the foam cushion pad that slides on the back rails and came with (at least my) chair.