 After achieving critically acclaimed success for their debut performance of the single "Twins (Knock Out)", which was performed on SBS's "Popular Songs" on November 6, 2005 for the first time, the group was scheduled to release an official single of the song.However, a digital single of "Twins (Knock Out)" was released instead with three more brand new singles available for download on November 8, 2005.The full album, which included all of the singles in the "Twins (Knock Out)" digital release and several other new tracks, was released on December 5, 2005 in South Korea.