The 127-film format is one of many that cropped up during the last century, and all but disappeared after some time. Nowadays the big stars are 135-film and 120-film (220 also, which is twice as much film on a 120 roll).
I've mentioned the 620-film format in my post about the Kodak Duoflex TLR, which is the same size negative as 120-film only on a different (and uncompatible) spool.
Some great cameras were made for the 127-films. The image size is most commonly 40x40 mm which is 12 images on a roll. The second most common seems to be 40x25 mm which produces 16. A rare one is the 40x65 mm.
I got me a Foth Derby 127 camera a while back (in the picture above). It didn't work. They rarely do, I came to realize after some research. That's not strange, really, since they were manufactured before the war, and sported cloth shutters similar to your Canon SLR:s and rangefinders of the 50s and up to the eighties. Glue and cloth ages a tad in 70-odd years. The Derbys with working …