What goes on in 23 seconds, comes off in 1 second, is rated to 10,000 lbs. To fully appreciate what we have accomplished with our mechanical restraint design you have to be familiar with the existing art.
Some manufacturers use plastic and others natural materials like leather and sheepskin.
Almost all of them need locks. The slotted leather restraints do not form fit the wrist securely and have been known to break. It is the 21st century and the world's largest and best known manufacturers of mechanical restraints are using 18th century technology complete with spring loaded metal lock and key and a thread-through design to keep them closed. If you have ever used them you know that placing them on a struggling and combative person is extremely difficult. This is old technology, and the industry needs to get with the times.