Check the listing for details. PolarStar - Fusion Engine Nozzle for G36-AEG Series. Condition: New. Listed at 23.00 USD. There are currently 6 different nozzles available for the PolarStar PR-15. Each nozzle has a different bore diameter which allow the operator to shift the velocity adjustment range up or down. The air nozzles are color coded in order of increasing velocity. The color coding also allows field and event staff to easily identify and confirm the safe FPS limit of an airsoft rifle using the Fusion Engine system. Note: The velocity with a given nozzle and pressure can vary depending on the length of the barrel. Therefore a shorter barreled will always yield a lower velocity than a long barreled. Readings were taken shooting a .2g BB through a stock VFC barrel/hop-up assembly at 120psi. Color and size of inner barrel: Green: 315-325-365fps Gold: 350-366-400fps Blue: 380-405-435fps Black: 425-457-475fps Silver: 445-494-515fps Red: 500-550-590fps The chart should read as this example: Black: (275mm) = 423fps, (380mm) = 457fps, (509mm) = 476fps