Yah, Frank that is it except all metal and sturdy. I've been doing some milling of rifle magazine tube hangers out of 1.25 round steel. So say for instance I need roughly .725 for the inside hole on the hanger but it has to be offset to allow for the male dovetail. I would like something that I could set at 1/2 of the .725 and scribe on the end of the round stock to get an idea of where I need to be. I have been using a compass but it has not way to measure distance on the tool itself. I've been guestimating using my calipers to get the rough distance of the compass. You would think that they would make something like shown above except a more sturdy, all metal