Basically these handcuffs are a pair of Hiatt steel darbies model 104. What makes them unique and the Number One of my Top Ten is the fact that they were given to me by my fianceé Nele on the occasion of our engagement.

One of the locktubes is engraved with my fianceé's name...

...and the other one with the date of our engagement.

These restraints were patented March 10, 1925, by Jacob Oliver McKenzie. In his book "Modern Handcuff Secrets for Magicians" the author Dick Norman describes them as follows: "...the mitts were designed to completely enclose the prisoner's hands, which were, in turn, fastened to a belly chain to prevent these unusual cuffs from being used as a weapon. The theory behind this particular pattern was that in the event the guard fell asleep while transporting a prisoner on a long train journey, the prisoner could neither make use of the keys or be able to handle a gun. However, production of this item was stopped after only several dozen pairs were manufactured. The reason...was that these cuffs proved to be too good, making the wearer completely helpless to a point where personal needs could not be taken care of, and accompanying guards highly objected and refused to cooperate to this degree. Since railroads have strict rules about unshackling prisoners during transit , the cuff was used no further, and became the only locking device to be discontinued because it was too good."  

Currently 20 sets of these mitts are known in the hands of collectors. The item you can see here surfaced in South-America, and it will have to be found out whether it is one of the known 20 sets or possibly set number 21.

The picture below shows you the restraint in the open condition. Once the hand is inserted the hinged part of the mitt is locked over the palm. To prevent the hand from slipping out an additional chain is placed around the wrist.

On the following pictures you will see several details of this rare restraint.

The term "Berliner" describes a family of hand restraints that have several features in common. The center of the handcuff consists of a single lockcase  which engages the two bows and a bar that separates the hands when the restraint is applied. The bows and the seperating bar are connected in a single hinge opposite the lockcase.

So far I have seen five different styles of Berliner handcuffs that probably were produced by different manufacturers. This style of handcuff was used in German prisons from the late 19th century until the 1920s or 1930s and possibly the use continued even after these decades.

The handcuff that is shown on the next pictures is a Mühlenfeld No. 113, among handcuff collectors it is better known as "The Dortmunder". The Mühlenfeld company was placed in the village of Barmen - one of the five villages that united in 1921 to found the city of Wuppertal, my hometown - and it produced all kinds of police and prison equipment including belts, sabres and restraints.
The No. 113 handcuff of this manufacturer features a single lockcase in the center of the cuff into which the two bows engage. The bows are fastened to the cuff in a single hinge, the metal loop is used for locking the cuff to a set of leg-irons, a belly-chain or a fixed object. In fact the Dortmunder handcuff shows all features of the Berliner family of hand restraints that are mentioned above.
The picture below shows the handcuff with the bows fully closed...

...and below you can see the Dortmunder in the opened condition and some more details of this rare restraint.

This handcuff was made by the Horst Stein Company of Munich, Germany, probably in the 1920s or 1930s and may have been used in German prisons through the time of World War II.

The bows of this restraint consist of bicycle-style chains which are covered with a rubber tubing to prevent injury of the skin. There is a single lockcase in the center of the handcuff and the appearance of this item very much resembles the Berliner-style handcuffs that are described above.

The picture below shows the area of the lockcase where the bows are inserted. Please note the metal fitting that, when it is turned... 

...180 degrees (as shown below) will reduce the circumference of the bows to accomodate to fit smaller wrists.

This handcuff was invented by Horace Lilly, member of the U.S. Marine Corps at the time of the Civil War. It never was patented and became famous, because it was used on the assassins of President Lincoln. Irons of this type also were used on Lilly himself, and as the story goes, he died during an attack of delirium tremens with his irons on.