RA Tech Magnetic Locking NPAS Complete Bolt Carrier Set for GHK M4 GBB Airsoft

RA Tech Magnetic Locking NPAS Complete Bolt Carrier Set for GHK M4 GBB Airsoft Steel Construction Airsoft Bolt Carrier Set Features an NPAS (Negative Pressure Adjustable System) Allows for easy tuning of FPS (Feet Per Second) levels for GHK M4 rifles Design For Upgrade the Original Parts More Durable Suitable For GHK M4 Gas Blow Back GBB Airsoft Gun