Frequency Zero was a sound wave that the purrgil could hear. These purrgil were creatures who traveled through space and had the ability to jump into hyperspace. It was not used anymore by 1 BBY. During the time when Lothal was being freed, Ezra Bridger gave Mart Mattin, Wolffe, and Cikatro Vizago the job of broadcasting a signal on Frequency Zero. This attracted a big group of purrgil. They then destroyed the blockade that Grand Admiral Thrawn's Seventh Fleet had put up around Lothal. Furthermore, they took Bridger, Thrawn, and the Imperial Star Destroyer Chimaera far away into space.