As Country Joe and the Fish's popularity grew, the band relocated to San Francisco in early 1966 and became popular fixtures at the Avalon and the Filmore Auditorium. On June 6, 1966, the band recorded a second self-produced EP, which was packaged separately from the "Rag Baby" magazine and, upon its release, debuted the new psychedelic rock incarnation of the group. The EP fulfilled the band's ambitions to incorporate electric instruments into their music, effectively melding the instrumentals and pioneering an early template for the musical subgenre of acid rock. It included McDonald's compositions "(Thing Called) Love" and "Bass Strings" on the A-side and the six-minute "Section 43" on the B-side. Music historian Richie Unterberger praised "Section 43", saying its "Asiatic guitar, tribal maracas, devious organ, floating harmonica, and ethereal mid-sections of delicate koto-like guitar picking rivaled the Paul Butterfield Blues Band's "East West" as the finest psychedelic instrumental ever". Within three months, airplay of the EP spread across the new so-called progressive radio stations, reaching as far as New York City, and establishing Country Joe and the Fish as a nationally relevant musical act.