The holders are threaded for 6x1mm nozzles.  There are two versions.  The first is 4x3 and has holders and labels for 0.80, 0.60, 0.40 & 0.25mm nozzles.  The second version is 7x3 and adds holders and labels for 0.50, 0.35 & 0.30mm nozzles. The Gcode file has manual filament change for printing a two color holder as shown in the photo.