RXW = Asian
Apparently the original MM20s came with adjusted Swiss ETA movements; well they did, until the Japanese courts shut down the Ken Trading / RXW operation when Panerai filed suit for copyright infringement. For some reason, people on Timezone love 'em, but you can easily find better quality reps if you look hard enough.
That's not the case with any of RXW's latest offerings, especially the "Plasmir Milgraph" series. Same Asian 7750 and Seagull ST-20 movements found in the usual Panerai rep offerings, but the watches are 3x the cost.
There are also a number of "Marina Militare" watches out there that are supposed to be from RXW. They're seen frequently on fleabay, PMWF, and even Timezone. Most of those aren't really from RXW and are, rather, poor Panerai reps that are just missing the word "Panerai" from the dial.