f(x) performed '4 Walls' and 'Diamond' for their M Countdown comeback

The long wais is finally over as f(x)'s promotions for '4 Walls' has finally begun!

Starting with M Countdown, here's their comeback stage where they performed 'Diamond' and '4 Walls'~

♥ Preorder f(x)'s 4th album '4 Walls'

♥ More about f(x)'s '4 Walls' here