Nature Plan Premium Bird Gravel includes tiny gravels which birds should have in their gizzard for an easy digestion. It helps the transport of oxygen in the blood,muscular growth of birds and usage of enzymes with calcium it has. Nature Plan Premium Bird Gravel contains important minerals for skeletal structure of birds. It assures a natural protection against stomach diseases and diarrhea with charcoal it has. It absorbs the toxic substances in intestine. It is suggested that you should regularly keep some gravel in a different cup in the cage. Ingredients: Natural shells,small gravels, red clay, charcoal.