small enough to carry in your wallet, quick enough to be done in a minute, and impactful enough to justifying using it. i go with a "what are the odds" presentation;

what are the odds i turned over the red kings? what are the odds i turned over the king of hearts? now, what are the odds you chose the only king with a different back?

I'll start by saying I have a soft spot 4 Royal Magic. As a kid I had a brick-and-mortar magic store in Toronto called browsers den of magic that I went to every weekend. I would walk there and they always had all of the classics of Magic on the back shelf Royal magic was a staple. This is a trick that I saw as a kid but never purchased and I totally forgot about it. This was over 30 years ago. So happy to have found this. It's all about the presentation. If you ham it up slowing it down this goes over really well. I think it's important to show the envelope empty and take your time to show that there really are only four cards. Showing that the chosen card is the only one with the different colour back is an awesome surprise ending that leaves people pretty dumbfounded. It may not fool a magician but it will fool everyone else and if it doesn't you just need to practice a little bit more. Highly recommended especially for this price it's basically a steal. The only downside is that they are not bicycle cards but as a packet trick it's definitely not required. In addition the card start in a envelope and the envelope is closed so you don't see the cards at first. This is a no-brainer to throw in the middle of any card set.

Good for kids.

Here is a version of the B'Wave plot that offers a completely free choice of any King in a packet of four - which choice is revealed to be the only king reversed in the packet and with a different colored back. Like all versions of this plot the cards cannot be examined, but this can be gotten around with good presentation. Cards are printed on Royal Magic card stock (i.e., not Bicycle) but I personally don't mind the difference. First off, most lay-people don't care about one kind of card stock or another, and different cards for this effect are justified by the cards being in a separate packet. Recommended.