Kagamine Rin & Len, codenamed CV02, are Japanese VOCALOIDs developed and distributed by Crypton Future Media, Inc., and were initially released in December 2007 for the VOCALOID2 engine. They are part of the Character Vocal Series and are both Character Voice VOCALOIDs. There has since been numerous installments such as additional voice banks dubbed 'Append' as well an update to the VOCALOID4 engine and an English vocal. They are the second set of vocals for Crypton's VOCALOID Character Vocal Series.