Fully upgraded polarstar F2 Engine krytac mk2 spr/dmr with maxx hop up/ rhop. The upgrades are as followed: Prometheus 6.03 509mm barrel with the option between a rhop or a purple prometheus bucking (comes with both), a maxx hopup, a tunable speed trigger ( currently tuned to a fraction of a millimeter fires it), a magpul stock, a grs grip, a suppressor to fit the extended barrel, a fore grip, the scope, and obviously the polarstar F2 engine. It also comes with a 7.4 25C lipo battery however it does not come with the FCU. If you have any questions please ask OBO