I was just setting up my Beseler 67 to print some 6x6 negatives and I'm a little confused; I went to put a negative into the Beseler #6741 6x6 negative carrier only to discover that the mask in the carrier is isn't square! It's 6.35cm wide, and 5.4cm tall. The images on my negatives are 5.6 x 5.6cm - square. Is this mask designed for 6x6 AND 6x7? Why doesn't it say 6x7cm on it, if that's the case?

Thanks in advance for clearing my confusion :-)