Handcuffs are restraint devices to secure an individual’s wrist close together. They comprise two parts, linked together by a chain, a hinge, or rigid bar. Each half has a rotating arm which engages with a ratchet that prevents it from being opened once closed around a person’s wrist. Without the keys, the handcuffs cannot be removed and so the handcuffed person is unable to move his or her wrists more than a few centimeters/inches apart, making many tasks difficult or impossible. This is usually done to prevent suspected criminals from escaping police custody. Handcuffs with double locks have a lock-spring which when engaged stops the cuff from ratcheting tighter to prevent the wearer from tightening them. Double locks also make picking the locks more difficult. Plastic restraints, known as wrist ties, riot cuffs are lightweight, disposable plastic strips resembling electrical cable ties. They can be carried in large quantities by soldiers and police and are therefore well-suited for situations where many may be needed, such as driving large-scale protests and riots.