The album title has multiple meanings. Since the performances were selected by Phil, they are the ones in his "zone". It also refers to the so-called "Phil Zone", an area directly in front of the bass amps onstage where some fans would stand, feeling the full-impact of the vibrations of Lesh's bass-playing. Lastly, it is a reference to the TV series The Twilight Zone. Lesh stated that, in addition to selecting personal favorites, he wanted to compile rarer material that may not have been released as part of a complete concert.[2]
The album includes a 30+ minute version of "In The Midnight Hour". Lesh said that he picked it because someone accused them of playing it for 45 minutes. He then tried to find the longest version. The album also includes "Hard To Handle" from an audience tape of the 8/6/71 concert. The audience recording was chosen because of the high quality.