Sorry Doug that I failed to mention it was you who taught me these good tricks to enhance effectiveness with this Protractor. I feel it at times it is impolite to mention another person's name without thier permission.
Thank you for adding, and reminding us about the parallax error, and how the aligning both first surface, and reflected lines will enhance alignment while looking at the grid. Mark
Thank you for adding, and reminding us about the parallax error, and how the aligning both first surface, and reflected lines will enhance alignment while looking at the grid. Mark