The rock track "A Chuck" by Mehrad Hidden featuring Reza Pishro was originally supposed to be included on Mehrad's album *Sefr*, but due to what was described as a difference in style from the album, it was instead placed on the collaborative group album *Frequency*.
This song (which marks the first collaboration between the two) refers to the hardships of the musical path and how Mehrad and Reza reached their current status after overcoming them.