Hi All. I've recently been given a box full of darkroom equipment from a friend. According to the previous owner, everything I need is there. With all the stuff I was also give a "Lucky p-66" enlarger. It came with two negative holders, one 35mm and another much larger one which I'm assuming is medium format. Now, I am really keen on purchasing a second hand medium format camera soon and I want to make sure that the camera I purchase is compatible with all my stuff. The dimensions of the hole in the negative carrier is about 57mm x 57mm (sorry American friends but I don't know what that is in inches). So is this standard 120/220 size ? I was looking at some Mamiya rz67's and m645's. They obviously have different negative size, so would both of them work in this negative holder ? Apologies for my newbness!