The MP5-SD is a variant of the MP-5 in that it is fitted with an internal sound suppressor. The MP5-SD was designed during the mid 1970s. The MP-5 submachine gun is one of the most recognized and prolific firearms in modern weaponry. Developed by Heckler & Koch GmbH during the mid 1960s, the MP-5 was produced upon the company’s success with the G3 battle rifle. Using much of the technology that was favored from the G3, the MP-5 and its variants are offered in various calibers and configurations to meet the needs of any law enforcement or military units engaged in close quarters combat. Since its introduction the MP-5 has been adopted by countless police, security and military forces around the world. Some of the more notable users are the British police and elite SAS units, American police and SWAT units, the F.B.I., and the US Navy and Marine Corps. To this day the MP-5 is still only manufactured by Heckler & Koch and found in numerous arsenals.