how do you add a ballast weight to it?
PETER M I do not recommend this product. It wore out very fast.
RUSSELL D I zip striped a piece of rebar to the bottom. Works well.
RICHARD S There are d-rings that you could suspend a weight from, however, I would not recommend this float for avid spearos. To use once in a while, or while traveling, is about the only reason I would consider it. Mine lasted maybe six weeks, and I don't use a float that often.