This is our last TMP 9mm pistol comes with a top rail and our Arm brace and 2 US made 30 round mags. the barrel is the standard 9mm trilug patter and threaded in 1/2×28, ships with out back pack and patch. This recever is compatible with all available UMP calibers, its a simple roll pin to swap in a new barrel. Fo caliber change you need a semi carrel, barrel and mag. German carriers will required to be milled to fit the semi receiver, Theres lots of 40 kits out there as well as 45 so you can swap between calibers in under 2 minutes with a hammer and a punch on your lap.