This is a physical product: a 2020 PreDate Calendar, printed with the Aronson stack.
No year is printed on calendar, so it can be used indefinitely.
It comes in a pocket-size black vinyl folder.
Note: This product is discounted by $5.00 from the retail price b/c of a small glitch.
No memorization required. The calendar does the work.
You don't need to know anything about the Aronson stack, but this calendar is a good choice if you want to learn the stack.
If you want to learn a different stack, like the Mnemonica, then order that version of the PreDate Trick Package.
If you know a card stack, the trick looks even better.
Includes a link to video instructions.
Also includes printed instructions.