The prototype of the heavy tank and the new 75mm gun was ordered from the Institute of Military Technology of the Hungarian Army (HTI) in 1941. The problem was that the HTI did not have any gun designer and production departments so they had to choose from an already existing gun and try to modify it. The engineers chose the 18.M field artillery gun - 8 cm Feldkanone M.18 - which remained in service since WW1. The HTI ordered the modifications of the gun from the Swedish Bofors company which willingly accepted.