I just got the newest version of the Holga, the 120N. It seems that it
came with new bells and whistles that the older version (I think I had
the 120S) didn't have - spool tensioners, a "B" exposure mode, and a
6X6 mask.

Anyway, I completely forgot I had that mask thing. I'm not really sure
what it does. The film I have in my camera now has 16 exposures in it.
And I think I was supposed to use the mask. Will my pictures come out
with a little border, or something, without the mask?

And if I have 12 exposures, then I just use what's in the camera
already - the 6x4.5 mask?

Enlighten me.

Thanks.