One frequently needs a straight-edge to check for ringers, measure the six inches for a point's distance from the stake, or calipers to measure the closest point. I've found three tools for measuring: the "Davis Tool," the "Pit Boss" and the "Horseshoe Hooker."
Here's my photo of (L-R):
Davis Tool w/round file, Pit Boss, and Horseshoe Hooker.
I use a "Davis Tool" which can come with or without a file (used to be just a flat file, and now can come with a round file). I use the one w/o a file since I carry a separate small round file. I've found that a flat file cannot get into the rounded areas of my horseshoes. The "Davis Tool" has a flat edge for measuring ringers, the flat edge has a notch to hold around the stake to measure the six inches for a point, and it has calipers for measuring the closest point. And, optionally, a flat or round file. These all fold in like a pocket knife. The calipers are the deciding factor why I prefer the Davis Tool.
The "Horseshoe Hooker" can measure for ringers and points (and pick-up the shoe) as can the "Pit Boss," though the "Pit Boss" has a tapered end for measuring the closest point and a grasping area to hold it.
If you are trying to decide what to use, find a pitcher who has one of these tools, borrow it for a bit, and see what you prefer.
Ron & Polly's Horseshoe Pitching Supplies has various
tool images so you can see how the Davis tool and Hooker are used.