As a Utilize action, you can use Manacles to bind an unwilling Small or Medium creature within 5 feet of yourself that has the Grappled, Incapacitated, or Restrained condition if you succeed on a DC 13 Dexterity (Sleight of Hand) check. While bound, a creature has Disadvantage on attack rolls, and the creature is Restrained if the Manacles are attached to a chain or hook that is fixed in place. Escaping the Manacles requires a successful DC 20 Dexterity (Sleight of Hand) check as an action. Bursting them requires a successful DC 25 Strength (Athletics) check as an action.
Each set of Manacles comes with a key. Without the key, a creature can use Thieves’ Tools to pick the Manacles’ lock with a successful DC 15 Dexterity (Sleight of Hand) check.