No secret, the CocoPuree Air Purifying Bag is filled with just one main ingredient - Formulated Coconut Based Activated Charcoal. This incredibly powerful activated charcoal/carbon filters are small pieces of carbon, typically in granular or powdered block form, that have been treated to be extremely porous. It is so cavernous, in fact, that just one gram of activated carbon can easily have a surface area of 500m2 or higher. These carbon filters adsorb exponentially more contaminants and allergens than traditional carbon. The more porous the activated carbon is, the more contaminants are adsorbed. We use military grade coconut based activated charcoal in our purifying bags, the same composition being used in gas masks.