Calcia is made with calcium carbonate which is a safe, highly absorbed form of calcium. Also, unlike calcium citrate, calcium carbonate is less likely to cause gastric reflux (heartburn). The other type of calcium is coral calcium. This is simply calcium carbonate which has been mined from coral; it offers no clinical advantage over normal calcium carbonate, and may contain higher levels of lead.
Calcia offers a full 500mg of calcium with high potency vitamin D, in a small easy-to-take tablet.