Our fiber filter balls are 100% polyester fiber.We use the best quality raw materials purchased from Shanghai Petrochemical. Shanghai Petrochemical is the top three polyester fiber raw material supplier in China.Our raw material has passed the REACH TEST, which means that 205 kinds of test are passwd. It's show that the raw materials are non-toxic, environmentally friendly, very healthy and will not cause any harm to the people who use it.Filter ball has good water permeability and breathability.