''The M4 series of tanks developed in the United States had many mass-produced variations and is said to be the premier medium tank.<br>The M4A1 Duplex Drive amphibious tank used an early improved model as a base and was equipped with a waterproof skirt and a propeller drive by the Country of Black Tea. It was also known as the Sherman DD.<br>Use them to launch amphibious landings from the sea.