Full metal tracer unit for use with AEGs. The tracer unit adds a glow effect to glow in the dark BBs as they exit the barrel. Excellent for night games! This is a great alternative to higher priced tracer units but still works great! 4 AAA Batteries included. Fits on any barrel with 14mm Counter Clockwise Threads. Keep in mind that removing the orange tip on any AEG will void the warranty.