It may help someone, but it appears that the spacing on the bearings is 26x28mm I'm not sure why that isn't included (oh, 5mm bolts) - I created a CNC drilling for them at 25x28 and had to redrill it - I had measured a bunch of times and it wasn't super easy to get the correct measurement. I've been having it sit on my table since last fall (to be fair, I did have sextuple bypass surgery so didn't get back to it for 3 months), but it was pending making the bracket that I needed. And my latest attempt is off, apparently by 1mm, so I'm going to redrill the bracket and hopefully, it will come out perfect this time.However, it otherwise seems like a very strong, stiff rail.. and if you need it stiffer you can always mount it to something stiffer - although, I've not seen any flex it in at all. The bearings seemed to run smooth, and are adjustable using two bolts to change how tight they glide on the rail.Of course, I'd use a dry lube on the rails and the bearings, because I'm pretty sure whatever you are using this on will create some kind of dust/splatter that will get on the rails and if you used grease, would get into the bearings. True for any bearings/rails.Happy CNC'ing! I'm considering getting a pair of these to use to run a pop-up shelf to come up out of my island in my kitchen...Enjoy!
CS 
