These Baoding Balls are made of solid copper metal from US copper mines. Copper's elemental properties make it one of the best conducting metals of energy such as electricity and heat. It's ability to conduct energy is believed by some people to have healing powers by conducting healing energy. Copper is also an essential mineral to humans.
A 1.5" pair weights about 1 lb. and a 2" pair weights about 2.3 lbs.