Compilation by Winfried Zinzow. Produced 1964-69 by Decca & Fontana Records.
Tracks 1 - 12 originally published as "Unit 4 + 2, Concrete And Clay" [or 1st Album?],
Tracks 13 - 22 published as "Unit 4 + 2"
Tracks 23 - 29 are additional Singles A/B sides (1964 - 68)