106 ?

What is the significance of this number?

I am thinking it is spool code; the # 220 is also on the box as well.

Only 8 exposures (6x6 IIRC - not sure but probably.)

Will such film fit (and work properly) in my Mamiya 6x7 120 film holders?

My Fuji 6x9 has provision for a short roll, 4 frames instead of eight. I seem to remember reading somewhere that they were only marketed in Japan. The marking on my camera calls it "120 4 exp." I've never seen such a roll.

Peter Gomena