4, 5 and 6 refers to the three groupings – quartet, quintet and sextet – taped at two July 1956 sessions. The results of these dates are typical of the type of recording Prestige was doing then. Although these were not in the jam session format the company also pursued in these days, the emphasis is on blowing. In addition to the ballad standards, handled by alto saxophonist McLean in the quartet context, there are originals from pianists Mal Waldron ("Abstraction") and Kenny Drew ("Countour"); and the already classic "Confirmation" by Charlie Parker. McLean and Donald Byrd had a chemistry going at the time, evident on "Abstraction" and "Contour." Mobley's mellowbop tenor adds further color to the ensemble and another strong solo voice on "Confirmation."