Pinking Shears Instructions that were included with the Model C in 1938-1949: Backs

The sheets are about 3" × 9-1/8", which matches the inside dimensions of the box.
Also see page for all fronts.
In the box with the second generation Model A's there was a similar instructions.

Started 1938
Pinker-insert-1938-2
Started 1942
Pinker-insert-1941-2
Circa 1944
Pinker-insert-1943-2
Circa 1946-1947
Pinker-insert-1945-2
1948 - early 1950
Pinker-insert-1948-2