Chick 2 weeks and older need fine grit to grind whole grains because they don't have teeth. We've combined fine limestone and granite grit with diatomaceous earth, Redmond Brand mineral clay and rosemary powder blend. 5 lb bag. Diatomaceous earth and rosemary support healthy digestion. Just the right size for chicks 2 weeks and older. For helping chickens process and digest the grains and food they eat.