Which of the following is NOT a type of handcuff mentioned?

The option that is not a type of handcuff is MK VI. This designation is not recognized within the standard classifications of handcuffs used by law enforcement and correctional agencies. The other types mentioned, such as MK IV and MK V, are established models of traditional handcuffs, while Flexi cuffs refer to a type of disposable restraint used in various situations where traditional handcuffs may not be practical. Understanding these distinctions is essential for recognizing the tools and techniques available for restraint in law enforcement scenarios. By knowing which models exist and which do not, officers can ensure they are trained and prepared with the proper equipment.