This item is not one I own myself, but an inferior brought it along for me to use on it for a session. I find a sub is either very turned on by their nipples or very turned off, rarely do you find indifference.
Nipple play usually has the initials TT, or tit torture. Some men go to extremes to have their nipples stand out as much as possible. I have in the past placed pegs on a sub’s nipples, and rubbed them with ice-cubes. I find it best to have a sub’s hands bound when doing TT. This way they have to beg if they want you to stop. It is always good to have a sub beg.
With the sub who brought this item I had he bound spread eagle, and then placed the clamps on his nipples. I then pulled at the chain until both clamps had been pulled off his nipples. From his hardon he was clearly loving this. At one point I put a clamp on a nipple and the other clamp on his foreskin, it was fun to watch him squirm whilst bound. After awhile I was fucking the sub, he was on his back with his hands bound and socked feet on my shoulder. As I pounded its hole I saw the chain so I paused and put the clamps on its nipples. I then placed the chain in its mouth. As I fucked him I told him to move his head up. This way he was pulling the clamps himself whilst I concentrated on my cock in his hole. He loved this and pulled the clamps off. He groaned so deeply I put them back on and told him to do it again.
UPDATE: I have now purchased this item; let me know if you want to try them out.