SilverStone Technology RMS09-20 Heavy-Duty Ball Bearing Sliding Rail kit for rackmount Chassis, SST-RMS09-20

tldr; If you're looking for functionality, these do exactly what they're intended to do. If you're looking for the ultimate server rails, maybe keep looking. I took a star off solely because they could be a little nicer for the price. Longer version: So I was a little worried about these based on the three other customer reviews that exist as of this writing. However, I most often find negative reviews are a result of user error, so I ignored them and charged on ahead. I was not disappointed. The instructions are fairly clear. Depending on the bracket, it may take a fair amount of force to initially expand the sliding joint to adjust it for your rack depth. One of mine spread quite easily, the other took some force. I was able to release both with just my hands, but to avoid scraped knuckles, I would recommend bolting one end to your rack, and lightly tapping the other end with a hammer. This is a one-time ordeal, once you break it free, it slides quite easily. The mounting points in the instructions are generic, your screws may be placed slightly differently depending on the case, but installation is fairly intuitive. Other than confirming that force is all you need to adjust the depth as described above, I didn't use mine at all except for the purposes of writing this review. The rails definitely don't "sound" smooth as you rack the chassis in and out, but they seem to work fine and since we're using these to install the system into a server rack, I never intended access the internals very often. If you are planning to slide this in and out multiple times per day... it'll probably still be fine, it just won't sound great. These rails are rated for 99 pounds. I probably have ~45 pounds on mine (the RM45-360 weighs 25 pounds alone). I think I might be more concerned if I were approaching that 99 pound rating, but that's difficult to do with the cases these were designed for.

I do not understand how these are so bad (currently using them with a RM45-360 case if that's relevant). I've used other Silverstone rails and they're all significantly higher quality (used RMS05-22 rails with a RM44 case, and RMS08-20 rails with a RM22-308 case). These rails are noticeably less substantial than anything else I've tried and slide far, far worse (they sound like they're grinding). Plus, these take a step back in installation ease and instruction quality. If I had other options I'd use them! Giving these 2 stars, because I guess they do work? If you're hardly ever moving your case they might be fine enough. But if you've tried other Silverstone rails the user experience really sticks out as poor.

Rails simply do not work as intended; they're a pain to put on the server and then they don't extend, stop, or retract where they're supposed to. Doesn't matter how much fiddling you do with the "up/down" switch on the side of the rails that's supposed to enable smoothly retracting the rails. Even when properly assembled with the server, it feels like there's sand in the ball bearings when sliding the server in/out.

I used this rack with the accompanying RM61-312 (6U) case from Silverstone. Admittedly, it is a heavy case given its size and being loaded up with 12HDDs, but it's well within the weight limit of these rails and doesn't inspire confidence. The rails flex inward pretty noticeably, but they have been holding so far (1 month). The instructions are also not great. It wasn't clear how you expand the rails to fit the depth of the rack (turns out you just pull really hard). The instructions also don't say what to do if the rails get stuck when retracting during installation (turns out you just push really hard to get past the blockage and it should be good from there)