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.
In 1939 only 75 acres in the Waimea area were devoted to agriculture. By the war's end that had increased to 518 acres. During the war an airstrip was constructed which later was to become Waimea Kohala Airport, The town's first entertainment hall and sports center was built. As detailed by Gordon Bryson in his Waimea Gazette article Waimea Remembers Camp Tarawa : Waimea leapt into the twentieth century because of the technology and plenty that seemed to have followed the Marines into town.