Constructed of nylon for dimensional stability and flexibility, the Flex-Cuf was designed to be a quick, temporary alternative to handcuffs. The unique Strength Barb System contained within the Flex-Cuf head makes them virtually pick-proof. It features a smooth inside surface, combined with rounded edges that help to minimize the chance of abrasion or tissue damage. The Flex-Cuf wasdesigned to be a quick temporary alternative to handcuffs. It features a unique strength barb system contained within the flex-cuf head makes them virtually pickproof. Nylon construction offers dimensional stability as well as flexibility.