Wondrous Item, rare
You can take a Utilize action to place these shackles on a creature that has the Incapacitated condition. The shackles adjust to fit a creature of Small to Large size. The shackles prevent a creature bound by them from using any method of extradimensional movement, including teleportation or travel to a different plane of existence. They don’t prevent the creature from passing through an interdimensional portal.
You and any creature you designate when you use the shackles can take a Utilize action to remove them. Once every 30 days, the bound creature can make a DC 30 Strength (Athletics) check. On a successful check, the creature breaks free and destroys the shackles.
Do these serve as manacles too like they did in 2014 dnd?
As far as story hooks go, this looks like it makes for a better thing to be used against the party, when they arrive at a new dimension and are deemed criminal spies.