CAL-MAG-FORCE 2:1Nutritional Support for your Bones! Superior skeletal support for bone health. Prairie Naturals CAL-MAG-FORCE 2:1 provides an optimum potency ratio of calcium to magnesium, 400mg of Calcium Citrate/Chelate & 200mg of Magnesium. This highly bioavailable formula is absorbed easily by the body. CAL-MAG-FORCE 2:1Tablets are an excellent choice for those at risk of osteoporosis or anyone wishing to "bone up on bone protecting nutrients".