The control token in Las Luchadras is a bracelet that slaps on and instantly renders its wearer an automaton, subject to the remote control.
Here’s something to note about this speculative technology. Orlak could have sold this, just this, to law enforcement around the world and made himself a very rich and powerful person. But the movie makes clear he is a mad engineer, not a mad businessperson, so we have to move on.
From Orlak’s point of view, getting the bracelet on its victim should be very easy. Fortunately, it does just that. Orlak can slap it on in a flick. But it’s also trivially easy for a bystander to remove, which seems like…a design oversight. It should work more like a handcuff, that requires a key to remove. It can’t look like a handcuff, of course, since Orlak wants it to go unnoticed. But in addition to the security, the handcuff function would enable the device to fit wrists of many sizes. As it is, it appears to be tailor-made to an individual.
As the diagram illustrates, not all wrists are made the same, and it would not help Orlak to have to carry around a sizing set when he hasn’t had time to secretly get the victim’s measurements.
Lastly, the audience might have benefited from seeing some visual connection between the bracelet and the remote, like a shared material that had an unusual color or glow, but Orlak would not want this connection since it could help someone identify him as the controller.