The girl group is gearing up for a comeback with all 5 members. Through the past few days, they've been dropping hints and spoilers for the 4th mini album 'Full Moon'. Today, the teaser revealed that their new title track is "??? / Dul Dul Dul" (an onomatopoeia similar to "brrr" in English). 

The full release of 'Full Moon' is set for November 7.