The "Standard" size I think is 96x99mm or something like that. Then there's the older Technika III boards, which were different for 4x5" and 5x7" cameras. Almost sqare, flat aluminium boards with a small notch in the middle of the bottom. The 5x7" boards were about 14x14cm, which is a little less than 6x6".
I'm just having a little buyers remorse. Always happens afterwards-) 140x140 would be nice but it doesn't make sense. Hopefully the seller is just confused about the type of lensboard coming with the camera. Either that or the camera has some sort of adaptor board.
It's an Ansco 8x10. I think from the picture and the text in the ad it should have a 6x6 board. The older models had a 7.5"x7.5" board. But the auction mentioned a "Technika lens board" so I'm confused-)