umbrella armory gearbox, has been tuned by umbrella I'm a cutting down my collection, you get the EMG BODY AND gearbox also have a star Wei 30k motor Gearbox contains Retro Arms 8mm gearbox Siegetek Concepts CNC chromoly steel gear set (14:1 ratio) Ultra fast rate of fire (33 RPS) Guarder V2 cylinder head Lone ventilated POM piston head Rocket Airsoft Full Steel Tooth Piston UA 8mm bearings Prometheus M135 steel spring Starwei 30000 RPM motor Gate Titan V2 MOSFET Rocket Airsoft stainless steel cylinder Rocket Airsoft MIM piston Guarder V2 tappet plate VFC M4 air nozzle Lonex ARL Precision gearbox shimming and fine tuning for optimized cycling