This dice cup is the only one in the market with normal shape. All other usually achieved are straight and always generates some kind of suspicion.
One of the first to use a non-straight dice cup was the great Pepe Carroll with his wonderful dice stacking routine. I leave a link for those who did not see it www.youtube.com/watch?v=qanLFPcT7C0

You do not only receive the dice cup but also 4 dice, to learn how to stack them. Finally, you will also have access to an online video with the explanation of basic stacking techniques and of some magic tricks with stacking dice. This video was filmed with a transparent dice cup, so that everything that goes on inside it, in order to stack the dice, may be fully appreciated.

You receive: Dice Stacking Cup Pro. 4 Dice. Online video with more than 20 minutes instructions (Spanish and English).