The 
Nuprol Shark Rainbow Tracer Unit
 is a compact airsoft muzzle device designed for high-performance visual effects. 
Key Specifications
Threading: Standard -14mm CCW (Counter Clockwise), compatible with the majority of airsoft rifles and pistols.
Multi-Color "Rainbow" Effect: Features internal LEDs that simulate a multi-colored muzzle flash. It can typically cycle through various colors or produce a "rainbow" flame effect as BBs exit.
Tracer Functionality: Illuminates green tracer BBs, making their flight path visible in low-light or night environments.
Design: Part of the "Shark" series, characterized by its aggressive, vented styling often found on compensators.