Clearly it's the Amulet 2. Link makes Ganon wear the ankle bracelet, allowing him to always know where he is. If he tries to leave Level 9 or remove it, it'll alert the authorities and he goes back in the Evil Jar.
Sounds good to me. I’m going with this unless someone comes up with a better theory.
Do not meddle in the affairs of dragons, for you are crunchy and good with ketchup.