The most rigid handcuffs ever!
We found a pair of handcuffs that are level 4 in rigidness (as we call it). Level 1 is chain cuffs, level 2 is weird Alcyon-link cuffs, level 3 is hinged cuffs, and these are level 4! Not moving at all! They look like naked speedcuffs? Who knows what they are. We love these, because they are the hardest to escape with the keyholes on the wrong side!