Heckler and Koch MP5/SP5 3-Position Retractable Buttstock. This 3 position retractable buttstock is manufactured and assembled for the Heckler and Koch MP5 and SP5 pistol/rifle platforms chambered in 9mm, 10mm, and .40 S&W. Fully collapsible and capable of retracted and extended 2 position form, this buttstock comes with an improved buffer and rubber buttpad while measuring at 10.5″ length. This buttstock features quality construction and is perfect as a replacement or for the next workshop project.