They work for whomever is holding the object. More specifically, they work for anyone that has this object inside of their person energy field (aura).
Interestingly, though there is a small portion of people that will absolutely refuse to admit that these effects are taking place, these objects even work for die hard “debunkers” and “skeptics.” Cognitive bias would have people conclude certain happenings as placebo or mere coincidences. There isn’t anything that can fully convince you if you come into this with attempts to debunk it. Skepticism with an open mind is a different story as skepticism is only natural for all the claims being made here. But if you do have an open mind, you’ll open your mind to some very interesting discoveries.