E-Cards consist of cards representing numerous candy and caramel companies. These cards, in general, are much rarer than tobacco cards.
Jefferson Burdick indirectly classified these as pre-1933 issues since his R-Card designation for later gum and candy cards was to be used for issues from 1933 and later. However, some issues, such as the 1929 Kashin baseball set (R316) don’t follow that identification – likely because Burdick was unaware of the exact year of issue.
Companies printing these cards often used many of the same images, likely to help save the time and expenses necessary to produce new ones. For that reason, some of the E-Card sets look alike and are distinguished by their backs.
Those backs, by the way, sometimes contained checklists of the entire set when it was feasible. Several of these sets were limited to under 50 cards and having the checklist on the cards when they were produced certainly was a help to collectors when the cards were first released. Some other backs don’t list the entire checklist, but do state how many cards were in the set.
Earlier E-Cards were generally colorful lithographs while later ones often used real, but black and white, images.
Here is a list of E-Card sets with boxing cards.