SF9's Zuho and Jaeyoon have released a special present for fans.

Zuho has dropped "Must Be Spring or Fall" onto his SoundCloud account, and the song is a duet with fellow member Jaeyoon. The song talks about missing someone, and comparing their love to spring or fall - in other words, getting warm, or getting cold. Zuho's rap matches perfectly with Jaeyoon's honey vocals.

Check it out below.