Silver Ion Cartridge for Hot Springs Spa, Hot Tub Silver Ion Cartridge with 4 Months Keeps Spa Water Crystal(Grey,4PCS)Brand: OBMAO Color: Grey4pack) Features: Contains 4 Types of Mineral Balls: The silver ion cartridge for Hot Springs spa uses 4 types of natural mineral balls,which can automatically add trace minerals to the hot springs,and can effectively reduce the amount of chlorine and bromine gas used. Efficient Purification Effect: The hot springs spa stick can significantly improve the look and feel of the water,reduce impurities in the hot springs,and keep