G&p 8mm gearbox set for m16/m4 electric gun (rear wiring)

Hi quality Full set custom internal box available
the best G&P parts and know how is installed into this device!!
m16 metal body parts included:
-selector
-magazine catch
-carrying handle
-trigger guard
-bolt catch button

internal parts
-sp120 steel spring
-8mm steel ball bearing
-steel gear set with delayer
-aluminum CNC cilinder head and seal nozzle
-ventilated piston head and steel/polyacetal piston
-steel trigger with switch and wire for rear battery

to install on hi quality rifle such Marui,g&g,g&p,king arms etc.....