reb---The ProMag has no markings on it. If you'll look at the plastic baseplate it'll look ecactly like your Ruger five rounder except it'll be a dull black & have no Ruger markings. Measuring the front of the magazine just the metal part measures 2.450" high. If you come up with a measurement of 3.360" then you have the same magazines as I mentioned before.
Good luck
Bushwack
Good luck
Bushwack