A spare turret to swap your tank to the other type, you will need to install a magnet into the ball joint, which requires sanding for them to sit nice and flush in your preferred pose
You can convert a Chichlid carrier to a tank (and back) with this kit by magnetizing the container, however you cannot convert the tank to a carrier (too many unique bits) and have installed the bottom peg holder on your carrier to hold the tank up after removing the container.
The missilefish bits require you to have magnetized the rear engines, and should probably be pinned in place due to the wings weight