Providence Tool Company Shackles

Here is a near-relic condition example of the Providence Tool Company leg irons. The seller states the cuffs are rusted but open and close. There is no key.  
 

Above, close up detail of the swivel.

Note the classic design of the Darby style cuffs and the distinctive traits that show these are Providence Tool Company: the angle of the hinge, and the round, flattened lock tube cap.