Versele Laga Oyster Shells 3 Coarse is a specially ground oyster shell based grit which provides your caged birds with an excellent source of calcium. Calcium deficiency is an all too common problem in pet birds as it is used for feather development, beak strength egg formation, however it is rarely found in their regular diet. Coarse grit provides birds with an easily digestible safe options for a wide variety of pet birds to use.