Sandwich effects have been around for decades and tend to have the same drawbacks; you can't show both sides of the sandwich, uses duplicates or requires a gimmick.
5 years ago, Nick Popa set out to find a solution for this beloved plot in magic that would turn all those limitations into a problem of the past. Imagine having the ability to have a card selected and lost using any borrowed shuffled deck. With no duplicates or gimmicks of any kind you clearly show both sides of your sandwich cards.
In an instant, a card visually appears sandwiched in between! It's their selected card!
Welcome to Nick Popa's, The Flash!