Birds have behavioral and/or nutritional needs for ingestion of soluble grit. Specially ground for all cage and aviary birds, HARI Oyster Shells soluble grit is completely digestible and provides a natural source of calcium which is required by all caged birds year-round. Oyster shells are a rich source of calcium required by all caged birds for stronger bones and health. They help to maintain normal cell function, which is essential when breeding for stronger egg shell formation. HARI Oyster Shells are soluble, and therefore digested by acids in the intestinal tract and will not remain in the gizzard or cause impaction.