In March 1944, the Adler company in Frankfurt submitted blueprint 021A38300 for a super-heavy tank called E-100, after the tank was proposed in April 1943 along with the other Entwicklung series vehicles.[5][6] According to the blueprints, the tank would be armed with a both a 150 mm gun and a 75 mm gun. Two types of engines were proposed: one was a 700 hp Maybach HL230, with a transmission and turning mechanism borrowed from the Tiger II.