NBU set with metal full teeth piston for M4

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.