Looks like glass but it's really safe plastic (like the Omni Deck).

An Ambitious card type of effect with an offbeat climax. Spectator takes a card from a deck and signs it. Performer pushes the signed card into the middle of the deck. The card magically jumps to the top of the deck. This is repeated again and again and finally for a climax the entire deck transforms into a solid block of clear plastic. You are supplied with a solid block of clear plastic to be used with poker size cards.

NOTE: This is not the "Omni Deck" which is the same effect made by another manufacturer.