5% Lugol's solution w/w (5% iodine + 10% potassium iodide + pure distilled water) and a very small amount of sodium selenite pentahydrate added so that each metric drop (20 drops/ml) will deliver 6.25-mg of iodine and 25-micrograms of selenium. With this concentration, someone taking 8 drops would be receiving 50-mg of iodine and 200-micrograms of selenium. Comes in a 4 sizes: 15ml, 30ml, 60ml, 250ml. Total iodine content is 12.6% or about 13%. Iodine and Selenium are needed for thyroid health and are the 2 rarest elements in the earth's crust essential to human life.---