Manacles consist of a pair of metal rings joined by a short chain. They are fastened around the wrists to restrain hand movement. Fetters are similar to manacles, but are fastened around the ankles to prevent running or kicking. Either manacles or fetters can also be called shackles. When a distinction is made between manacles and handcuffs, it is that handcuffs employ a lighter, more modern design with a built-in ratcheting lock. The two halves of some sets of handcuffs are connected with a hinge or bar instead of a chain, to further restrict movement.