The Turk is a dealer in Rome, that offers several high-end items. Among them are 3-star shotguns, Advanced Stealth Armor (otherwise only available through alliance with G22), and expensive stealth armor mods (Improved Digital Camouflage, Multispectral Flashbulb and Integrated Circuitry).
He should become available in Rome before Intercept Marburg at the Museum of Art.