My understanding is that Mec-Gar does make magazines for the P365 series, but they only make some of the available mags. If your magazine says “Made in Italy” on it, then it’s a Mec-Gar mag. If it says “Made in the USA,” it could be from either Checkmate or Pro-Mag (I believe Pro-Mag is the second USA vendor but I’m not 100% sure).