The radio station created songs that change genre when you listen to them on just one headphone. Working with Romanian artist Claudia Pavel, the radio station launched the Go Mono Anthem. It's rock if you use the left headphone, and acoustic if you listen with the right headphone.
Numerous Top 10 artists participated in the campaign, airing exclusive remixes of their songs on Radio 21: original versions heard in the left headphone and the exclusive remix in the right headphone. McCann Bucharest created the campaign.