Dietary supplement. The only legal Deca precursor. Learn; Apply; Grow. DecaVol converts at a high rate to Deca and is better than testosterone for building mass and strength with fewer side effects. Deca is prized as the perfect anabolic. DecaVol is the only product of its kind to convert to Deca in the body. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.