Carib Sea SCS00591 Cal-Stron Reptile Calcium with D3 Powder, 6-Ounce Calcium contains naturally occurring strontium carbonate with D3 and ultra-smooth texture Made from pristine coral sands and is phosphorous-free Features more digestible than oyster shell or calcite based reptile calcium Strontium provides greater bone density and egg shell strength It weighs 6-ounce