Two interesting things

 Above, this is a custom 4 point wrist and thumb restraint with connecting chain. 

It sold for $103.50 after 22 bids. 

The seller states "original vintage handcuff set" and "vintage handcuffs 2 piece set Smith & Wesson stamped" 

This is only partly correct, and I can promise you this is not an "original" restraint. 

The handcuffs are Smith and Wesson Universal Handcuffs (model M-1 currently) and the Thumbcuffs are Yuil. 

Yuil is a South Korean company producing high quality modern equipment for police and military, primarily restraints, batons and flashlights. A wide range of Yuil restraints is available on Handcuff Warehouse. 

I have the Yuil Thumbcuffs and they are actually pretty nice, other than a thin and "sharp" edge (other than the internal 'serrations') these are also higher security as they have a single, very small bit. 

I also have the Smith and Wesson universal hinged handcuffs. Smith and Wesson unfortunately only gave one option for the double lock on these cuffs, and that is a push pin, as compared to their excellent cheek plate slider and lever lock. The first pair I bought has faulty double locks. 

As cool as it looks this is absolutely a custom piece made in someone's workshop.

 

Above, here is an interesting example of a vintage design from Master Lock. The Master Lock Street Cuff is a bicycle/motorcycle lock which resembles nothing so much as a heavy duty, futuristic restraint. 

These locks use a tubular key much like a coin operated laundry.

This vintage design has an actual leg iron chain with O rings similar to Smith and Wesson 1900. Modern examples tend to use a heavy roller link chain as seen below. 

Sold for $124.50 after 16 bids.