I bought the heaviest nipple weights that I could find, 8 ounces per side. I bought two sets, so I can do 1 pound per side, or concentrate it all to 2 pounds on one side.

These are "Master Series", marketed mostly for CBT or nipple stretching.

Unfortunately, the clamps are not well designed, and tend to pull off unless I have a layer of fabric between the clamps and my nipples. I was hoping to be able to stretch my nipples, but because of the clamps, it is difficult to wear them for extended periods.