... 2nd Layer GAC + Antibacterial ballDeeply adsorb color, smell, chlorine, bacteria, heavy metals, halohydrocarbon and other harmful micro-organisms, improve the taste ... and anywhere.3. Tramping over hill and dale, no heavy burden but fast filteration of mountain water.4. More safe ... filter bag for emergency adsorb color, smell, chlorine, bacteria, heavy metals, halohydrocarbon, outdoor water filter bag