In order to connect the Power Recycling Vacuum Cube to the Central Vessel, the heights of the center flanges must be close (more tolerance with the use of bellows). I measured the distance between the bottom of the 10" side length vacuum cube and the custom aluminum base to be between 0.97" and 0.99", with an average of 0.976" (nominal thickness is 0.97"). I measured the custom aluminum base to be between 0.5" and 0.52" (nominal thickness of 0.50"). We will likely need a 0.01"-0.02" sheet to bring up the cube bottom to 1.5" above the optics table. We have shim stock to do this.