The MP5SD3 is the integrally suppressed variant of the MP5 with a collapsible stock. The SD (Schalldampfer, German for suppressor) series features a ported barrel that bleeds propellant gases into the suppressor body, reducing the bullet to subsonic velocity without special ammunition. One of the most effective integral suppressor designs in firearms history. Type: Submachine Gun Action: Roller-Delayed Blowback Caliber: 9mm Capacity: 30 Year introduced: 1974, Germany Weight: 7.5 oz Overall length: 31.5" Status: Active Military use: Yes Intended use: Special Operations, Military Use, Covert Operations