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. Gold CQB (275mm) = 350fps, Carbine (380mm) = 366fps, Rifle (509mm) = 400fps (The power range can change per the rifles barrel length and bore size so results may vary.) This product comes with a 6 month warranty provided by PolarStar Airsoft.