AE Max Masterkey is built using the Maruzen shotgun, Classic Army M15A4 SPC, and G&P Masterkey kit.  Upgrades to AEG and shotgun are extra.  The Maruzen spring shotgun can be upgraded to almost 400fps (with 0.2g bb's).  We can modify this gun to use a Crane stock and battery also or an M4 collapsing stock and PEQ2 battery unit.  For other Masterkey configurations, please email us.