The HK UMP is a German submachine gun developed in the 1990s by Heckler & Koch as a lighter and cheaper option to the MP5, despite both remaining in production. It can be interchangeable between 3 calibers: the UMP45 (.45 ACP), the UMP40 (.40 S&W), and the UMP9 (9x19mm Parabellum). The HK UMP has been used by several agencies and military forces including the U.S Customs and Border Protection.