Full NBU air system for power increase of the M4 AEG. Recommended barrel 300-400 mm. Set include:
- chromium-plated cylinder
- polycarbonate back pressure silent piston head with the bearing
- stainless cylinder head with double O-rings
- acetal nozzle with O-ring
- Light polycarbonate piston with the full metal teeth.
What is NBU? : NBU parts have increased inner diameter to hold more air capacity. It is ussually cylinder, piston head, cylinder head and nozzle. Typically sold as a complete set. It is recommended use M120 springs or higher to reach proper effect.