Linear Bearing designed for 608 (skate) bearings and M8 or 5/16" bolts. (File is in Inventor 2011 format, as well as STL). Designed for a 1/2" rod. Two of the six bearing holes are slightly oval to allow for adjustment via the set screws.Based on Dave Kush's Design (http://www.buildyouridea.com/cnc/hblb/hblb.html)Update #1 (06-OCT-2010):Update #2 (06-OCT-2010):Update #3 (06-OCT-2010):Set screw holes are sized to be tapped with a #6-32 tap. See image for details on bearing adjustment.