I think if you buy the smaller set you’re ok, as long as the side hex screw has the same size as the faceplate. Like I said, I was just overestimating based on appearance but there’s no context to the size in the picture so it’s better to go off a comparison to a relatively known size. I would think the screws Elektron uses for the faceplates are probably all the same after a certain point, the one inside the Digi holding the PCB are a little larger so maybe 3mm but even if it’s those screws it should still be within the right range.
@ammanuel here I dug up this thread which says side screws use a M3 for rack mounting, so metric 3mm and that means it might be bigger than the faceplate screw but is likely to be ok with the 3mm wrench. I think this should be accurate unless yours uses a special screw, but I doubt it.