Thank you. Unfortunately, I doubt that info.
The smallest IEM nozzle I’ve measured was cca. 5.6mm. However, there are numerous comments like “diameter of the nozzle … is a bit big”, “nozzle diameter is on the larger side but the length is short”, “metal nozzles are collared, wider than average in diameter”.
I’ve also found a claim that for Mega 5P, the widest part of the nozzle was 6.5mm.
So, if somebody has 5EST and a caliper tool, please enlighten us.