![1girl anorak ball_and_chain bird bloomers bone dress gothic_lolita lolita_fashion long_hair lowres oekaki original shitaiya solo stuffed_animal stuffed_bunny stuffed_toy underwear rating:s score:0 post #240568](/cdn_image/preview/f3/08/f3089b53ba8158af0a4a69fcda0a3d4e.jpg)
A heavy and dangerous to use crushing weapon that uses centripetal force for power. It uses a heavy ball-shaped weight like a flail, but the chain is longer and may not be attached to a handle.
A rule of thumb, if the weapon has a handle (especially a long handle) and the chain is under an arm's length, then the weapon is most likely a flail instead of a ball and chain.
For the restraining device, see the ball_and_chain_restraint tag.