Iron Restrictors are special devices used form extreme martial arts training. They are composed out of a compressed form of various iron minerals and are subsequently extremely heavy, weighing down the user and thus rapidly increasing their strength and speed.
The Iron Restrictors are built in the form of a harness that is applied to the arms and legs of the body in the form of a suit. The user wears these for an extended period of time and trains hard in order to get used to the weight. The iron restrictors are held together by extremely tight springs making movement of the limbs nearly impossible. Once the user has gotten used to the restrictors and they are removed, their strength, speed, and agility will have increased to all new devastating heights.