Progressive Laboratories Microcrystalline Hydroxyapatite (M.C.H.A.), also known as Micro-crystalline Calcium Hydroxyapatite Complex (M.C.H.C.), is derived from raw bone and prepared by a special low temperature process (below 37C) to preserve the protein content.
The calcium thus provided is in an extremely bioavailable form.
Vitamin D3 is because it is required for the absorption and utilization of calcium and phosphorus and is especially important for normal growth and development of bones and teeth.