The 
NUPROL M4 Flash Hider K
 is an airsoft barrel attachment designed to fit 14mm CCW (counter-clockwise) threaded barrels, a common standard for M4/AR15 airsoft replicas. 
 
 
Key Features and Specifications
Thread Compatibility: Designed for use with 14mm CCW external barrel threads.
Construction: Made from high-strength metal for durability.
Design: Features a realistic design. It is also compatible with Angry Gun QDC suppressors and tracers.
Installation: Secured using a grub screw and comes with a stainless steel shim to ensure a perfect fit on the rifle's outer barrel.
Function: Primarily an aesthetic accessory for airsoft guns, it enhances the tactical look of the replica. (In real firearms, a flash hider reduces the visible muzzle flash signature).