Double your faces, double your fun...
There's a face on one side, and when you flip it over, there's a face on the other side. This is the reason they're called double-faced playing cards, and they're useful. Use them in a regular deck, or use them all at once, there's a lot of ways these things can be used to mystify and amaze.
Each deck is identical to the other, and the best thing about them is that they can be used with your RED back deck & your BLUE backed deck, The choice is yours, that's how versatile these things are.
*(Box color varies)