Conn’s description in 1931:
This model represents the highest developments in euphoniums, for there is nothing lacking. To the smooth, accurately proportioned sound passages resulting from the hydraulic expansion process, has been added the two bell-front type detachable, adjustable bells. The larger bell enables the player to throw the sound in any desired direction and the smaller bell enables the performer to use echo or trombone effects to give variety and life to the tone coloring. The fifth valve is used to control this extra bell while the fourth valve is used for the low pedal notes. For the performer who is looking for the ultimate in euphoniums, this, unquestionably, is the instrument.