After releasing sweet album jacket photos earlier today, SISTAR's newest sub-unit, SISTAR19, has released their debut single, "Ma Boy"! In contrast to the high tension music video teaser, the song is sweeter in quality.�The girls have been working with Brave Brothers since their debut, and he's their producer once again for this romantic track about the nervous feelings of a young woman in love. As expected, Hyorin's explosive vocals and Bora's rapping are a perfect match, so check it out below! Tip: FalcolnChern