Perma Guard Diatomaceous Earth Fossil Shell Flour Food Grade 2 lb (10/Cs) Perma-Guard OMRI certified Diatomaceous Earth is the purest food grade fresh water amorphous silica diatomaceous earth available Perma-Guard is derived from fossilized diatoms remains It is approved as an anti-caking agent in feed not to exceed 2% of rations fed and meets FDA regulations to be considered Food Grade