How do you want to use the PolarStar Fusion Engine in an MP5 body? Watch this video made by PolarStar Airsoft's Jordan as he does everthing in just 10 minutes... "Have you ever wondered just what is involved with configuring the Version 2 Fusion Engine for use in a gun besides the M4? In this video we demonstrate the versatility of the Fusion Engine by showing how easy it is to switch between gun models. We start out with the engine installed in a complete PR-15 CQBR and in a matter of ten minutes Jordan has swapped over all of the components to finish with it installed in a MP5."