Grand Funk Railroad's second, self-titled album, also known as The Red Album, is considered their best blues rock album. It was released in December 1969 and became a gold record by June 1970. The album features improved sound quality and more diverse styles compared to their debut album, including hard rock, heavy psychedelia, blues, and country. The album's success helped the band gain popularity, and they even opened for Led Zeppelin in 1969. However, their performance was so well-received that Led Zeppelin's manager had to turn off their equipment to end the show.