There are five different Zener cards: a hollow circle (one curve), a Greek cross (two lines), three vertical wavy lines (or "waves"), a hollow square (four lines), and a hollow five-pointed star. There are 25 cards in a pack, five of each design.
The esper being tested must be able to determine what the contents of the card are correctly.
In Toaru Majutsu no Index, the card's material was changed from vinyl to ABS resin, which was instituted by the United States of America in 1992 due to a trick that the fingerprints on the card made it possible to determine the card's contents.
Toaru Majutsu no Index
- Main article: Sisters Arc
Three Stories Arc
- Main article: Three Stories Arc
In the anime adaptation, cards are shown on Touma's coffee table during his attempt at finishing his summer homework.
Toaru Kagaku no Railgun
Level Upper Arc
- Main article: Level Upper Arc