Sundown Naturals Liquid Filled Calcium 1200 mg plus Vitamin D3 provides you with the nutritional support you need to help maintain strong, healthy bones. Calcium is the primary mineral responsible for strong bones, and Vitamin D aids with Calcium absorption. In addition to promoting bone health and density, Calcium also supports healthy muscle contractions and nerve function, while D3, a potent and active form of Vitamin D, assists with maintaining a healthy immune system.