A digipak is an alternative to the standard CD jewel case, consisting of a custom printed card packaging that holds CDs in plastic trays. Digipaks allow for artwork and extras like lyric books to be included. The Nirvana album "Nevermind" used a blue-themed digipak containing rare band photos and album information. Soundgarden's digipak was a 4-panel pack with one CD and information booklet. Metallica's 6-panel digipak spread content over more pages, including 2 CDs and a booklet with band history.