The ingenuity of this design is breathtaking. The ‘plug’ consists of a small grub screw which is unfastened using the flat head screwdriver one end of the key. The other end of the key is screwed into the barrel. When the first thread finishes you then engage the driver into a further nut which engages with the exterior pin securing the handcuffs closed. You then back out of the barrel by ‘reversing’ out and replace the plug to completely seal up the barrel. Very hard to escape!
Internal circumference 19.4 centimers.
Weight: 460 grams