I have to give away a sealed pack of six black correctable ribbons for
use on Canon electric typewriters, models AP 200/300 and AP 400/550.
According to the boxes, they are compatible with all Canon models that
fall within those model number bands.
The brand is Fullmark, and the ribbon size is 8 mm x 210 m.
Photo attached.
They were bought by a friend who stocked up on them - just before the
typewriter threw in the towel...