Increase hand strength and endurance: These are mainly used in martial arts (especially Kung Fu or Hung Gar style) training. Wearing these on your hands while practicing punches or blocks helps to quickly increase hand muscle and wrist strength.
Speed and balance: After practicing with heavy rings, your hands feel much lighter when you take them off, and your punching speed increases many times over.
Bone strengthening: These help in conditioning or strengthening arm bones and muscles to withstand impacts during hand-to-hand combat.