Revolver is the album that made the Beatles recording artists in the absolute sense of the term. Their previous six albums had demonstrated John Lennon and Paul McCartney's increasingly ambitious songwriting skills and the group's competence with a range of musical styles. But the productions, while strong, were undistinguished.

The Cowcaster is guaranteed to turn heads. That’s because it is one. The one-of-a-kind guitar, designed and built by artist Brent Gandy of Amarillo, Texas, brims with custom features — from Von Dutch–style pin striping on the back of the neck to a hand-carved bull’s head headstock — all of which are connected to an authentic bull skull.

George Harrison’s withering indictment of Britain’s progressive tax system was chosen to open the Beatles’ most progressive musical effort to date. Opening with a rasping cough and a droll count-in, “Taxman” kicks off Revolver in startling fashion, demonstrating both Harrison’s growing sophistication as a songwriter and Emerick’s budding talent for sculpting guitar tones.