A restraining device is an object used to limit the movement of a person or animal. Two examples of restraining devices are shackles and manacles. Shackles are metal rings that are connected by a chain and are used to restrain someone's wrists or ankles. Manacles are similar to shackles, but they are usually made of leather and are used to restrain someone's wrists. Both shackles and manacles are commonly used in law enforcement and prisons.