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.
This was a Roman victory. The Romans captured some of Pyrrhus' elephants and riders, and paraded them through the streets of Rome. Pyrrhus left Italy with very little of his original army. In 272 BC, Rome defeated Taras, adding southern Italy to its growing empire. In that same year, Pyrrhus was killed in the streets of Argos, trying to add southern Greece to his territory. Rome was now the master of Italy and had stood up to a Hellenistic army considered one of the best in the ancient world.