#shackle  a U-shaped bar; the open end can be passed through chain links and closed with a bar
  supertype:  bar.artifact  a rigid piece of metal or wood; usually used as a fastening or obstruction of weapon; "there were bars in the windows to prevent escape"
  part of:  padlock  a detachable lock; has a hinged shackle that can be passed through the staple of a hasp or the links in a chain and then snapped shut

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