The lead single off the groups 2nd album reaching #8 on Billboard and #2 on the Dance charts. Note: cover sleeve has bpm written small on the top left corner.
A1 "What You Don't Know (Atomic Mix)" – 6:35
A2 "What You Don't Know (Might Hurt You Beats)" – 2:36
A3 "What You Don't Know (Radio Mix)" – 4:10
B1 "What You Don't Know (Bass Mix)" – 7:09
B2 "What You Don't Know (Crossover Mix)" – 6:36
