Same as Polychorus. Kurt had two of them apparently, and used them on the Unplugged show. However, I don't know what songs he used it on. I don't think he used it one any songs, but Guitar World says that he was arguing with MTV techs over the various qualities of the Echoflangers.
THE FORGOTTEN MARINES OF TARAWA. During late-November 1943 one of the most savage battles in the history of the Marine Corps took place on the tiny island of Betio, located in Tarawa Atoll. The capture of this island took three days and cost the lives of 990 Marines and Navy Corpsmen. In addition to these, another 2,200 were wounded.
More than 1,000 U.S. troops were killed in action and some 2,000 were wounded in only three days of fighting at Tarawa. Word of the heavy casualties soon reached the U.S. and the public was stunned by the number of American lives lost in taking the tiny island.