Do you know?

I realize that the new NGC holders have new security measures on the back. However, I have seen some with prongs that enable you to see the edge like the presidential and other with no prongs like the conventional holders. It seems the only consistency is that all coins with edge lettering have prongs. But I have seen other coins with no edge letting with prongs also and some like the convential holders. How do you know what you will get? Pronged or non-pronged. In addition, with the new $20 2009 Ultra High Relief gold coin coming, will the NGC holder accommodate the thickness of this coin.