The self-propelled version of the 60cm siege mortar was ordered in June 1937. General Karl Becker of the Artillery was involved in the development; hence the name Karl was used to describe the gun. The driving trials were held at Unterlüss in May 1940. Delivery of the six production vehicles took place from November 1940 to August 1941. In February 1941, discussions commenced. Concerning increasing the range of the weapon, and in May 1942, 54cm barrels (Gerät 041 ) were ordered for the six vehicles. At a conference with Hitler in March 1943, it was stated that the first 54cm Gerät 041 would be delivered by June 1943, and the third, by mid-August. The 60cm and 54cm barrels appear to have been interchanged as required. In 1945, US forces captured vehicle II with a 60cm, and vehicle V with a 54cm. Item No    00209 Item Name    Morser Karl-Gerat 040/041 on railway transport carrier Bar Code     n/a Scale    1:35 Item Type    Static Military Artillery Model Brief    Length: 840 mm Width: 99.4mm Height:133mm Total Parts    1251pcs