 "Poor Tom" is from sessions for "Led Zeppelin III", having been recorded at Olympic Studios in June 1970, and "Walter's Walk" is a leftover from the sessions for "Houses of the Holy".Side two

Side two consists of three outtakes from the band's previous album, "In Through the Out Door".The opening track, the uptempo "Ozone Baby" was recorded at that album's sessions at Polar Studios, Stockholm in November 1978, as was the rock'n'roll styled "Darlene".