f(x)'s Sulli and actor Gong Yoo coupled up to endorse LG's new smart phone Optimus Z.

The pair have already completed filming on their CF, and they have recently released the CF. In the commercial, the two slip each other their numbers with the aforementioned LG Optimus Z phones that can work as both a phone and a laptop. Though Sulli is loved for being her cute self, she showed a mature side to her image in this CF.