It is noticeable that the roll lengths (in metres) given in the DUCA book are in each case almost exactly double the actual DUCA play rolls. The photo shows the DUCA reel No 10 "Murmelndes Lüftchen". Roll length in the catalogue: 21,5m. Actual roll length of the punched area of the play roll: 10.75m. As already suspected in expert circles, it can be assumed that the receiving rolls had double lengths and could therefore record more finely. The length was halved in the transfer from the mother roll to the playback roll.