BSN Cell Mass

For young people today it seems important that they build up their muscles. I have a couple of nephews that have gotten quite into this body building stuff. I wonder if they have used a product called bsn cell mass? It's suppose to help in assisting the body to increase in size and also increase hardness and strength. I guess I haven't asked them if they are taking anything or if they are just on their own. Their hard work is starting to show however.