This is a modern treatment of Peter Kane's classic Jazz Aces from Another Card Session (ref. p. 8), that uses J. N. Hofzinser's transparent cards as published in Card Conjuring (ref. p. 163 in the Fisher-Sharpe translation).
Effect: The performers, while explaining how Casino blackjack dealers use a device called a BJ Scanner to discretely check their hole card, demonstrates that the use of such a device doesn't keep a clever dealer from secretly switch hole cards.
The trick comes with four, superb, Hofzinser Gaffed cards made by Jeremy Hanrahan.