... dia. 2 - 15mm (as your request)3) Main ingredients:energy, kieselgur, anti-bacteria material4) Function: anti-bacterium and activation5) ... environmentally friendlyAdvantages: 1) Tourmaline powder can persistently release negative ions, emit far infrared ray.Hence, it can purify ... , clothing ornament and filter medium 3) After tourmaline negative ion powder is made into ceramic ball and ceramic brick, ...