 It also gives the operator a lot of comfort by being placed right in front of his eyes next to the controls that adjust the machine and it has not a single wire that can get trapped in the cluttered quill area.A very common setup is to have a regular DRO with glass scales on the milling machine's table and a separate vertical quill DRO.This gives a resolution of 0.005mm to the table position and 0.01mm to the quill.