The cravat is based on a the "Scavanger's Daughter" device.
The ankle and wrist bars are basically a "bilbo": an 18" metal rod with one end flattened out to prevent anything sliding off and the other end with a hole in it to pass a padlock through. The iron "U"s are bent so that there is a small loop at the end of each stem of the "U" through which the rod is passed. The middle part has the neck ring and pivot at one end and two loops (matching in either side of the part) in the middle and other end of the part.
To install, the middle part is placed around the neck. One ankle and one wrist are placed in their loops with the rod through the loops. The rods are installed into the middle part and the other loops are placed on the other ankle and wrist and installed on the rods. Two padlocks are applied to the rods at this point.
The "bilbos" can be used without the middle part as well.
The cravat is said to produce intense pain in the whole body with dispatch due to the contorted position the body is held in by its rigidness. What is clear is that it is very immobilizing and quite functional as a stand alone bondage device.