This m4 converted in HPA with a polarstar F2 and a gorilla FCU bluetooth is great
has several red accessories. Can be easily adjusted with your android or apple device thanks to the gorilla FCU.
internally you have a red external barrel and internally a pdi 6.01 with maxx hopup + led
has a maxx trigger easy to adjust without having to take everything apart
battery titan 350mah 7.4v