Matched pairs of Royer mics are consecutively serial numbered and shipped together as a perfect match. Consecutive serial numbering adds value to the pair and shows that they're matched. Technically, two mics that are separated by more than one serial number cannot be "matched." However, Royer mics are extremely consistent. Any two Royers of the same model should work well as a pair. We keep records on every Royer microphone. If you'd like a mic that closely matches one you already own, chances are we can find one for you in stock. (Note: The sensitivity of Royer mics has gone up over the years, so if you have an older Royer and want it matched to a newer one, we may have to work on your current mic to bring it up to newer spec. This is not necessarily recommended, as older un-modified microphones tend to increase in value.)