f(x)'s Luna revealed a picture taken with her members.

"f(x) 4walls," posted Luna on her Instagram on Wednesday along with a picture.

In the picture, the members of f(x) are dressed in school uniforms while sitting in a classroom together. Luna is wearing a gray jacket on top and behind her are the rest of the group, all making different poses.

f(x) had released the first spoiler for their new album 4 Walls on this day, so many fans are assuming that this picture was taken while they were filming for their new album.

4 Walls will be released on October 27.