this series of Fusion Engine air nozzles allows you shift the velocity range of your rifle up or down to best meet your requirements. Nozzles are easy to install and typically take less than 5 minutes to change out on most models from start to finish. 

Each nozzle is machined from aluminum and comes with both the internal and external o-rings. The nozzles are color coded with a hard coat anodizing for easy identification. 

Results with a .20g BB using a 6.05mm barrel at 120psi. 

Green CQB (275mm) = 313fps, Carbine (380mm) = 325fps, Rifle (509mm) = 363fps 
Gold  CQB (275mm) = 350fps, Carbine (380mm) = 366fps, Rifle (509mm) = 400fps
Blue   CQB (275mm) = 380fps, Carbine (380mm) = 405fps, Rifle (509mm) = 435fps
Black  CQB (275mm) = 423fps, Carbine (380mm) = 457fps, Rifle (509mm) = 476fps
Silver  CQB (275mm) = 446fps, Carbine (380mm) = 494fps, Rifle (509mm) = 514fps
Red     CQB (275mm) = 500fps, Carbine (380mm) = 550fps, Rifle (509mm) = 590fps 

(The power range can change per the rifles barrel length and bore size so results may vary.)

This PolarStar product comes with a 6 month warranty 

specs:

FE Nozzle Type: M4/M16
Series Build Material: Aluminum  
Nozzle Length: 1.745 in.
External O-Ring Size: 014-70D
Internal O-Ring Size: 7mmx1.5mm-70D

Green- Bore Size: 0.0781 in.
Gold-   Bore Size: 0.0890 in.
Blue-   Bore Size: 0.0980 in.
Black- Bore Size: 0.1160 in.
Silver- Bore Size: 0.1285 in.
Red-    Bore Size: 0.1610 in.