The Wolverine GEN 2 The Wolverine Inferno airsoft HPA engine is based off the previous SMP system and is designed to drop into nearly every popular gearbox on the market with no modification. Please choose from the drop-down menu for the exact size and fit needed. Comes with a standard M4 air nozzle for Version 2 gearbox. If you need a different nozzle, please include it in your order notes comment or email us for V3 specifics. M249 comes with M249 nozzle.