The 3.7cm Flak43 was developed by Krupp to replace the earlier 3.7cm Flak 18. The gun was used as the armament of the Ostwind mobile anti aircraft tank as well as being mounted on the sWS - schwerer Wehrmacht Schlepper. The kit depicts the Ammunition trailer towed by the sWS or Sd Kfz 7 Half Tracks that accompanied the Flak gun. See my other MACO items for sale for the sWS and 3.7cm Flak 43.