The Entwicklung series (from German Entwicklung, "development"), more commonly known as the E-Series, was a late-World War II attempt by Germany to produce a standardised series of tank designs. There were to be standard designs in five different weight classes (E-10, E-25, E-50, E-75 and E-100) from which several specialised variants were to be developed. This intended to reverse the trend of extremely complex tank designs that had resulted in poor production rates and mechanical unreliability. The E-25 designs, in the 25-50 tonnes weight class, were to be the replacements of all Panzer III and Panzer IV based designs, with Alkett, Argus and Adler, with involvement of the Porsche firm. Designer TigerAce1945
