Feature：

●CNC machined aluminium made with black anodized finish.

●For GHK M4/AR GBB Rifle.

●Providing a greater customization possibility and a wider range of barrel lengths to choose from.

●5.1″ length for GBB-180mm inner barrel, OB-51.

●3.9″ length for GBB-150mm inner barrel, OB-39.

●2″ length for GBB-100mm inner barrel, OB-2.

●All outer barrels are 14mm CCW thread with M3x4mm set screw for alignment.

●All outer barrels are also for AEG or other same spec of outer barrels to extended.