This is a Bazooka 2.36-inch anti-tank rocket, one of the most famous U.S. weapons of World War II. It was popularly known as the Bazooka after a musical instrument of a comedian of the time, Bob Burns. The secret of the Bazooka's success was its shaped charged warhead that could penetrate the steel armor of tanks.
The Bazooka was fired by a standing infantry soldier or in a kneeling position and could also be fired in a prone position. The Bazooka entered combat in 1943 and gave good results against German tanks in Tunisia, North Africa, then became widely used with improved models that saw service during the Korean War. This object was donated to the Smithsonian in 1989 from the U.S. Army Ordnance Museum.
This object is on display in Rockets & Missiles at the Steven F. Udvar-Hazy Center in Chantilly, VA.