"4 Walls" is a song recorded by South Korean–multinational girl group f(x) for their 2015's eponymous fourth Korean studio album. The deep-house and UK garage track was written by Jam Factory member Lee Seu-ran, whilst production was handled by production LDN Noise, singer-songwriter Tay Jasper, and producer Adrian McKinnon. It was initially released on October 27, 2015 by their label and Genie Music as the lead single, in conjunction with the release of its parental album, and later as a double A-side single with a new Japanese track "Cowboy" on November 2, 2016. An accompanying music video was also released, featuring the members witnessing themselves in different dimensions. It was the group's first single as a quartet since the departure of Sulli in August 2015, and their first Korean