Nylon "disposable" cuffs but with a twist. They can actually be reused as many as 6-8 times by unlocking them with a standard handcuff key rather than cutting them off. The cost savings and the fact that a sharp cutting tool is not needed to remove them makes them ideal in many environments.
In addition, with the use of a small auxiliary piece of plastic, two of them can be connected to form two individually tightening loops.