Early leg irons. No markings, no key. Some pitting. I believe these are leg irons because of the size of the openings. Approx. 4-1/4"x4" at outside of each ring; approx. 3"x3" at inside. Approx. 5/8" thick. As shown. - eBay
Seems that the person auctioning these had no idea what he had given the vague description. Despite this collectors did find that is was available given the final bid amount.
This set of handcuffs sold for $512 (Plus $13.25 Shipping).