No extra weight, you won't even notice the difference..
KEVIN N Thanks,Mark. Do you find this helps warmth wise? I'm diving in Monterey with a 7/8 semi dry and would like to beef up the chest a little bit.
MARK G Yes it does, I wear it under a 5 mil when the thermoclines hit the Atlantic side of Florida. I use 12 pounds with a 19cf Pony and don't adjust weight for the vest