It's time to prepare that spare M4 you have to take in this Fusion Engine Version 2 gearbox from PolarStar... "Have you ever dreamed of Polarizing your MP5, G3 or SCAR? With the introduction of the GEN3, now you can!  At first glance the GEN3 FEV2 looks very much like the GEN2 and, for the most part, the two are quite similar. However, unlike its predecessor, the FEV2 GEN3 is no longer just for the M4/M16 series rifle.