A miracle metal devised by the couturier/alchemist Pepe. Used to manufacture micromail, it has the remarkable capacity of being able to absorb any shock inflicted on it and to send it back the way whence it came.
Think of the Red Dwarf episode Justice World, where the Dwarfers are all subjected to perfect trial and punishment for their past misdeeds. Three of the crew are acquitted, but Rimmer is sentenced to over three thousand consecutive life sentences to reward his criminal negligence for his part in the manslaughter of the Dwarf's original crew. Here, in the Justice Zone, any act of malice, aggression, hate, violence, et c, automatically blows back on the aggressor. Lister discovers this when he tries to set fire to a cell - only to discover he has set his own clothing alight. Similarly, a thrown punch or kick has no effect on the victim - but it lands on the thrower with equal force. Lister later uses this to advantage by luring the psychopathic rogue simulant into the Justice Zone, where the Simulant destroys himself with his own violence.