Repti Calcium is an ultra fine Precipitated Calcium Carbonate Supplement. It is a phosphorus-free calcium supplement for reptiles and amphibians. It has a unique shape/high surface area per gram resulting in increased calcium bioavailability. Additional Information: Highly bioavailable source of calcium carbonate Free of harmful impurities (not from Oyster Shells) Use with reptiles that are able to meet their Vitamin D3 requirements.