Lego minifig compatible Custom SI-Dan Toys US M1 Army World War II helmet, fits on a minifigures head. M1 Steel Pot Helmet. The standard issue helmet of the U.S. military for over 40 years, the M1 Helmet is an icon of American history. The perfect helmet for all your classic US troops or any minifig soldiers who need a sturdy helmet to see them through battle!