polarstar f2 v2 m4 standard fcuThe Polarstar F2 is in theory a Mini Fusion Engine. It offers the same adjustment setting options and performance as the Fusion Engine in a cylinder size. The F2's dual solenoid design provides the same functionality as the legendary Fusion Engine, but in a more compact design. Dual solenoids allow the nozzle and poppet valve to be adjusted independently of each other (just like a Fusion Engine). This allows you to fine tune your unit to your exact