Trikolon were a very gifted trio from Osnabrück. As precursor of Tetragon, they played a very varied progressive rock. They even were influenced by classic and blues. Their only LP "Cluster" was already released in 1969. It was edited by themselves in a number of 150 copies. Thus it had been one of the most earliest works of this kind. Correspondingly modest were the means with which it was recorded, and here lies its only weak point. But whoever, for example, is listening to "Blue Rondo à la Turk", will be excited about the true firework performed on organ, accompanied by racing drums.