GHK M4 GBB High Cycle & Speed Bolt Kit

GHK M4 GBB High Cycle & Speed Bolt Kit Metal Construction (U ltra Lightweight) Design For Upgrade the Original Parts More Durable The Spring Strength is Perfectly in tune to ensure a Rapid Cycling Response with every Pull of the Trigger Suitable For GHK M4 Series Airsoft Gas Blow Back GBB Rifle