Towers Detective (Union Hardware)

 

Here is a set of Towers Detective Handcuffs, decent condition, no key, $99.95 or best offer, offer accepted. 

Here is a nice close-up detail view of the locking notches on the external surface of the shackle bow. Although it looks similar to a standard handcuff key hole, these require a different, larger single bitted barrel key. 

The single long link indicates these are from the Union Hardware era, when Union Hardware produced, marketed, and eventually bought Tower Handcuff Company in the early 1900s.