How these boxes of cards criss-cross within each other, is a mystery to the eye.
You pull out a red deck, but decide to put it back inside the box. Then pull out a blue deck, from the same box?? A real puzzler!
There are no instructions, so I'll tell you that only a red card is on top of a full blue deck. Open the box and slide the entire deck out, showing only the top card, they will assume it's a red deck. Put it back inside and this time, hold your finger on the red card, thru the natural cut-out at the opening and slide out the entire blue deck, and show all the cards. Play with this, you'll love it!