Restraints, (usually metal) often joined by a chain, placed around a prisoner's wrists or ankles to restrict their movement.(noun)
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Use "shackles" in a sentence
"The response - which calls the term shackles "an emotion-charged pejorative" - also notes that the restraints aren't intended as punishment, but deter fighting, disruptions and escape attempts."
"A creature bound by the shackles is considered to be entangled."
"The DC to break or slip out of the shackles is 30."