This combination is the one to challenge those escape artists out there!  It comprises a pair of Yuil Y-001 handcuffs joined to a pair of thumbcuffs with two rings.

When your prisoner is secured in this device you can offer him/her a key and they will still find it impossible to unlock themselves, mainly because it is virtually impossible to hold anything! 

Securing your prisoner with hands behind the back will prevent escape by picking the key up in their mouth.  A real challenge for the 'Houdinis' out there!