From the introduction:
The Sorcerer and Wizard Spell Deck II contains all the Core Rules class spells from level three through level four plus blanks, in a thick poker card deck format.
This spell deck allows players to easily reference their class spells and even manage their spell slots with visual representation. These spell cards have the full spell text and mechanics within, so no need to hunt down the rules, you have them at your fingertips!
You can even use multiple decks to represent your entire number of slots and memorized spells!