Originally manufactured in Germany in 1983, this firearm was reconfigured by S&H Arms of Oklahoma to match the "MP5K" configuration and act as a host for the included registered trigger pack. Hooded blade front and four-position drum rear sight, with a short barrel, vertical foregrip, and plastic buttcap with sling swivel. The original "shelf" on the rear of the magazine housing is solid, but has been altered to accommodate a functional "paddle" magazine release, and the left side of the receiver is marked to match the installed pack. The textured pistol grip has "S/E/F" marked selector positions.

Individually registered as a "Machine Gun Auto Sear" with the ATF prior to the 1986 registration cutoff, this trigger pack is configured for compatibility with "shelf" equipped H&K semi-automatic receivers, and registered for 9mm caliber. The pack is individually marked and numbered on the underside, with additional numbers on some of the individual components.