Ionic nano-particle colloidal silver, 24 parts-per-million in distilled water. This is a relatively strong solution, intended more for fighting active infections than for routine prevention.
Do not mix colloidal silver with any other substances; it is recommended that silver be taken alone. Needs no refrigeration but stays more potent when stored in a cool, dark place.
This strength comes in a stunning two-toned bottle that is even more beautiful than the photos show, which starts at the top in a brilliant raspberry red-pink and fades into an electric blue at the bottom. The 4 oz size comes in a cobalt blue bottle.