Cluster's second album finds them still in their Berlin phase, that of the amorphous analog electronic passages without the reference points of any actual rhythms. The tracks move along based on circular synth sequences that provide structure without the addition of overt tangible beats, such as what they would explore on subsequent albums after moving to the German countryside and collaborating with Michael Rother from Neu!, who would also join them in Harmonia and provide his trademark motorik rhythms for both bands. "Plas" starts out like churning machinery, then lifts off dramatically into expansiveness, evoking the scene in 2001: A Space Odyssey where the astronauts circle the moon in slow rotation to slowly reveal the sun in an ominous deep space daybreak; its analog shimmerings and pulsations are the obvious precursors to the ambient passages in Orb and Aphex Twin songs before the depth-charge bass and breakbeats drop in. "Imsüden" is monotonously repetitive, with a woozy spy flick guitar figure inducing vertigo over a swelling and ebbing synth motif and panning helicopter sound effects for over 12 minutes. The aptly named "Für die Katz'" is a brief playful interlude that is the aural equivalent of making a cat jump and chase after a laser pointer. The 15-minute centerpiece "Live in der Fabrik" comes closest to the UFOs-piloted-by-aliens-on-acid themes of their contemporaries Tangerine Dream, and manages to be space rock without the rock. Whether seen as frustratingly nebulous or trance-inducingly hypnotic, Cluster are nevertheless one of Krautrock's true electronic pioneers, and this is headphone candy at its finest.