The Beretta Px4 Storm SD 9mm is the Special Duty variant with a threaded barrel and suppressor-height sights. The rotating barrel system makes the Px4 inherently suppressor-friendly, and the SD variant formalizes that configuration for tactical and competition use. Type: Semi-Auto Pistol Action: DA/SA Caliber: 9mm Capacity: 17 Year introduced: 2010, Italy Weight: 28.2 oz Overall length: 7.6" Status: Active Intended use: Competition, Tactical, Defense