The basic engineering for all the German half-tracks was developed during the Weimar-era by the Reichswehr's Military Automotive Department, but final design and testing was farmed out to commercial firms with the understanding that production would be shared with multiple companies. Borgward[Notes 1] was chosen to develop the second smallest of the German half-tracks and built a series of prototypes between 1934 and 1937. However development was taken over in 1938 by Hanomag who designed the main production version, H kl 6.