I have 6 film holders 9x12 (Zeiss Ikon, Voigdlander) with sheaths and it seems they are all made by someone and they look grate. I have not yet use them with my new Voigdlander Bergheil but all exterior sheaths size are 89x120mm. So 1mm less than nominal 9x12 film size (interior about 1,5mm less).
Does it matter for keeping film flat or for film loading?
Does nominal film size are exactly 90x120mm?