Last week, Bingo Airsoftworks put online two videos covering two competing gearbox drop-in kits to convert AEGs into HPA-powered airsoft guns. The first one is the G&G M14 PolarStar Fusion Engine Breakdown and the second is the G&P Mk23 Stoner 63 Wolverine SMP Conversion Breakdown. Interesting on how they were able to fit these in these two types of airsoft guns which are not version 2 or version 3 types.