I think I'll just repeat what the previous reviewer said. I agree they aren't as slick as they could be, but they should be more than enough for something of a CNC project, a pair I plan to build soon. The hulls are a bit rough, but again that doesn't affect the movement. Warehouse. It is very good that there are adjusting screws. As already mentioned, very well packaged. Overall they are doing a great job and I would recommend them.