Bought these for a wood flattening project x-y axis to house a router jig. Overall they_e been great and do exactly what I want them to do, the only downside is that the base does not attach easily to the runners (drilled holes do not align) meaning I have had to fashion some brackets to allow for the runners to connect perpendicularly to the bar. The runners are Slightly looser than I expected even when tightened, however this is not much of a problem. Overall they do pretty much what they_e supposed to with just a little bit of creativity.