Edit 12/6/22: Stealtho reached out and offered to replace my set of wheels after improvements were made following customer feedback. The rep I spoke with stated they're using a new method of attaching the post so (hopefully) the separation issue is solved. While outwardly similar to the previous set, the new model I received has a beefier collar supporting the post that goes into the chair so I'm hoping that that and the internal redesigns are enough. I'll update my review should new/old issues arise. Edit 5/21/21: added a photo of the issue I discussed in my review. The axel turns out to not be removable so, with the aid of some vicegrips and a readily available ball end allen wrench, I tightened up the bolt and abandoned the idea of threadlok. Only took five minutes to check all of them and tighten them up a bit. If you're not in the habit of checking your chair every couple of months it's recommended as a little routine maintenance can be the difference between just having to tighten a bolt or breaking something or everything. I ordered these Jan. 24 2020 and the day of my review is May 16 2021, and this is for the non-locking version. For any context you might need I currently weigh a bit north of 200lbs (down from 250, though I partially blame the lockdown and easy access to snacks) and typically use my chair for 3-5hrs on work days and well over 12hrs/day on weekends. During lockdown my wife and I have sat in this chair together and these wheels were durable enough to support almost 400lbs as we rolled across the kitchen floor like maniacs right after putting these on. My computer and hobby desk is set up in a second bedroom so the thick carpet played havoc on the standard casters that came with my chair so after getting a workout throughout COVID lockdown I finally caved and went in search for replacement. I couldn't get details from a set of Herman Millers on the stem size before they went out of stock but these Stealtho wheels stood out from the rest of the offerings by merit of their design, and were also about $100 cheaper. I was ready to make a temporary upgrade till they came back in stock but these have held up to the point my first choice have been back in stock but I don't see the need to change, though one thing about them has me irked* which I'll get to later. If you have a chair on thicker-than-typical-office carpet, rollerblade style wheels like this are what you need if you move your chair frequently and don't want it to be a battle. I'm happy to say Stealtho wheels traverse over carpet fairly easily and, if you're on a hard surface, they roll like butter. I later upgraded to a polycarbonate chair mat so I get almost the same experience, though I've yet to find one large enough for my needs. That bring up a further bonus of oversized chair wheels which many people don't account for and that is they're much better for going OVER things, so when my chair occasionally rolls off the mat it's very easy to just get back on compared to what I imagine it is like with the stock office wheels. Cords also get rolled over easier, though that's neither a pro nor a con. First off, just toss any consideration of the the glow in the dark feature out - they barely glow and certainly not enough to warn you of your chair's location in the dark before your eyes would naturally adjust to the darkness. Second, these are very much opaque and not clear or semi-translucent as the pictures might make them appear. Last of these bullet points, if you're looking for a quiet roll, these are almost silent aside from a squeak or two which I blame more on the polycarbonate mat than the wheels themselves though they might slightly be at fault (see further down for my one gripe). When I spoke about their design a few things stuck out - rounded, smooth edges. I tend to fidget with my feet when I'm absorbed or rest them on the legs of the chair and I have yet to be poked by any corners and the structure of these wheels doesn't jut out from under the legs of the chair. The boxy body of other wheels can have this issue and if you've ever had your foot slip off onto the sharp corner of a caster it's not fun! I can also confirm that these did not mark my kitchen floor and have left ZERO marks on my mat and furthermore, despite a year and closing in on six months of heavy use, the elastic polyurethane of the wheels hasn't worn down * -----> Now then, my one gripe. While I've not experienced any mechanical or structural failure, if you would scroll up to the 2nd picture of the wheel from a low camera angle. If you follow the stem down under the wheel body you'll see a bolt. This is a hex/allen wrench bolt which the stem connects to. The issue I've found is one of my five wheels has developed a very minor lateral tilt because the stem and this bolt have come partially unscrewed which causes a temporary bind when the wheel needs to rotate to a different orientation. I can hand tighten by holding the small plate the bolt sits on which solves the issue short term, but because of clearance with the wheel I can't get a hex wrench in to actually get some resistance to tighten the stem up. I'm planning to see if I can get the axel off to disassemble each wheel and, after examining if it would help, maybe put some locktite threadlocker on to make it a permanent fix. Will update review if this is possible for those fellow DIY'ers. Overall, if you're looking for an upgrade to an office chair, I would say the $40 price tag may initially seem a bit high but if you get as much use as I have out of these they're a good purchase.