The Brügger & Thomet MP9 (Maschinenpistole 9mm, German for "machine pistol") is a submachine gun chambered for the 9×19mm Parabellum cartridge that is designed and manufactured by Brügger & Thomet. The MP9 is a selective-fire submachine gun. It uses 15, 20, 25, and 30 round transparent polymer detachable box magazines. It has three safeties: an ambidextrous safety/fire mode selector switch button (manual safety), a trigger safety, and a drop safety. The MP9 is a development of the Steyr TMP. The design of the 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.