Relient K has found commercial success with their studio albums, three of which peaked in the top 15 of the U.S. "Billboard" 200 chart: 2004's "Mmhmm", which debuted at No. 15; 2007's "Five Score and Seven Years Ago", their fifth and most successful album, which debuted at No. 6; and 2009's "Forget and Not Slow Down", which debuted at No. 15. The band has sold over 2 million records, with three albums being given gold certification by the RIAA. The band is also highly successful throughout the Christian albums and contemporary Christian music charts. On October 4, 2011 the band released a cover album "Is for Karaoke". On July 2, 2013, the band's seventh full-length album, "Collapsible Lung", was released. On July 22, 2016, the band's eighth full-length album, "Air for Free", was released. On April 24, 2020, they released "Relient K: Live" that includes 15 tracks that were only previously available on vinyl and were recorded at shows in 2009 and 2016.