The Brügger & Thomet MP9 (Machine Pistol 9mm) is a machine pistol designed and manufactured by Brügger & Thomet of Switzerland. The MP9 is a selective-fire 9×19mm Parabellum caliber machine pistol. It uses 15, 20, 25, and 30 round transparent polymer detachable box magazines. It has three safeties; ambidextrous safety/fire mode selector switch button (manual safety), trigger safety and drop safety. The MP9 is a development of the Steyr TMP. The design of TMP was purchased from Steyr in 2001. Differences from the TMP include a stock that folds to the right side of the weapon, an integrated Picatinny rail, and a new trigger safety.