It appears to me the gauge Joe illustrated uses the same principle of expanding "fingers" as used on the Galazan "Professional" bore gauge. I have one, and actually find it easier to use and more precise than the common type using 3 ball bearings. It works for all gauges (except .410) using only the single tool. There are calibration rings for all gauges included.

But it is a matter of personal preferance--both types work well.