CoiL
Member of the Trade: Wood Audio Accessories & Modifications
Nothing special, one is for nozzle chamber, second for back chamber which is just exited other way as usual. Imo, those port holes are placed really well as they don`t seem to be blocked by average ear shape, at least I don`t have problems with it. But despite the port holes, I`m sometimes having driver-flex, probably because of too fast insertion with deep fit - air can`t escape so quickly through port hole "filter" material (which is probably very "tight").Dual vent holes...interesting.
I will probably open my IT01 soon. I just need to make little "bracket" for opening, to not damage shells.