Antique Plug 8 Boer War

 Here is a very rare restraint which is similar to the Irish 8. Once the locking bolt is screwed down, the small threaded plug (visible at the bottom of this photo) is then screwed into the keyhole for extra security. These would be extremely restrictive to wear behind the back. 

They sold for $203.94 after 11 bids with one original key and the plug.