Nice piece of linear rail kit. I did tried it as it is, it works somehow, but the sliding blocks need to be cleaned. I'll soak them in metylated spirit for 1 day and a proper silicone grease after that, hopefully it will work well.
I don't feel like these are top of the line by any means but they do work great for the router sled that I made out of them. They are easily strong enough for the job and with a little filing on the casing for the bearings they rolled really smooth.