C4 is the third solo mixtape by American rapper Kendrick Lamar, then known as "K.Dot". It was released on January 30, 2009 through Top Dawg Entertainment (TDE). The mixtape contains 17 tracks and includes guest appearances from Lamar's TDE label-mates Ab-Soul, Punch, Jay Rock, ScHoolboy Q, and BO. The mixtape was heavily inspired by fellow American rapper Lil Wayne’s 2008 critically acclaimed album, Tha Carter III (C3), being mostly composed of freestyles over instrumentals from Wayne’s album in addition to a couple of original tracks.