Airsoftjunkiez show in this video how to install the Airsoftjunkiez Custom HPA KRISS Vector Chassis that they have in stock right now. This item is a complete drop in Chassis with either the PolarStar Airsoft F2 or Jack HPA engines. For easier installation, drop in kit also includes Krytac nozzle, tappet arm, tappet linkage and cylinder head. According to the company, it comes assembled ready to drop in.