Cuff

A cuff (also called a shackle or fetter) is a metal object worn around the wrist or ankle with the purpose of restraining a person's movements. In mainstream media, Smurfs are usually seen wearing cuffs attached to chains and metal balls when they are being held prisoner.

In the EMPATH: The Luckiest Smurf, Psyches constantly wear silver cuffs around their wrists and ankles as a sign of submission to the Psyche Master, who can use the cuffs to send electrical charges into the Psyches to punish them. Empath wore the cuffs during his time in Psychelia, which were only removed whenever he was sent to visit the Smurf Village for a year once every ten years. Empath eventually didn't like having to wear the cuffs, and was glad to be finally rid of them when he was released from Psychelia upon his 150th birthday.