Hobby Boss 1/72 German KARL-Geraet 040/041 on Railway Transport Carrier Kit

The 60cm "Karl" mortar was the largest self-propelled artillery piece in the German arsenal. "Karl-Gerät" (German literally "Karl-device"), named “Karl” by the Allies, was a World War II German self-propelled siege mortar designed and built by Rheinmetall. It was the largest self-propelled weapon to see service. Its heaviest munitions was a 24 in diameter, 4,800 lb shell, and the range for its lightest shell of 2,800 lb was just over 6.2 miles.

Each gun had to be accompanied by a crane, a heavy transport trailer, and several modified tanks to carry shells. The weapon was moved long distances via rail on a variant of a Schnabel car, the whole chassis was hung between two huge pedestal-mounted swiveling arms fixed to five-axle bogies.[8] When it reached its destination, the weapon was detached from its supporting arms, driven to its intended firing location, then the chassis was lowered to the ground to distribute the recoil forces more evenly in preparation for firing.