A flexcuff is a nylon restraining strap that can substitute handcuffs, expecially when the police
officer has to arrest several people (a flexcuff case can carry more than ten straps; a similar number
of steel cuffs would be quite bulky).
It can be placed on the wrists or the ankles
of the person in custody; it must be cut to be removed, therefore it's limited to a single use.
Hollywood has caught on - in the movie "Heat" the bank robbers flexcuff the security guards.