SISTAR 19 GONE BUT STILL AROUND

I dunno what's up with the title. XD
But anyway, is a SISTAR sub unit, duo SISTAR 19's comeback!
which feature SISTAR's main vocalist Hyorin and rapper Bora
It is said (In Wiki) The ’19′ in their name represents the age that girls mature into women, and it also embodies the sense of innocence yet uncertainty they feel.They aim to showcase these feelings through their lyrics and concept.

Pretty Successful if you ask me~=) 
The sub unit debuted with the single "Ma Boy"