Aluminum Handcuffs

This is an uncommon swing through design with a flat key. There is a makers mark that appears to read Taikai. The cuffs are engraved CNR for Canadian Northern Railroad.

These sold for $146.98 (actually $199.99 Canadian) with one key. 

The lock insert looks like it rotates like the Bean Cobb. The cuffs themselves are shaped somewhat like Takeda cuffs. There are modern swivels and 3 round links connecting the cuffs.