In the late 19th Century, cardboard premiums (BB cards, etc.) were originally inserted into cigarette packs as "stiffeners".
The "slide and shell" cigarette pack contains 10 cigarettes in the "shell" and the card was inserted between the shell and the
inside wall of the pack. Many early 20th Century packs contained 2 cards. In the Spring of 1911, TOLSTOI (or LENOX, UZIT)
packs contained a T206 and a T80 (Military Series) cards.
Perhaps this picture helps to illustrate what I'm saying......
TED Z