K-pop girl group Mamamoo released an acapella version of their song, “Um Oh Ah Yeh” as a surprise after they finished their album promotions.

In the video the group is seen singing the song with just the beatbox rhythm and no music in the background.

Fans were surprised to at the group’s vocal and rap skills and how well they were able to perform even without any sort of music.

Mamamoo, who are also avid fans of the acapella group Pentatonix, received much inspiration from them when making this special video.

The group released their second mini album this past June and held promotions for six weeks straight.

Mamamoo will be holding their first fan meeting since debut on August 23. Tickets will be available through Interpark starting tomorrow.