Use:
This is generally a nipple toy. Specifically, it is designed to trap blood in the nipple making them larger and more sensitive. They are extremely adjustable so the user can control the sensations. The 7" chain holds the rope on both sides together.

The rope that the knots are made of isn't the softest product. I have fairly sensitive skin, and while I can use these, I often avoid them if my skin is being extra sensitive because they are scratchy.

Fit:
Here is the one major downside I have with these. When I first purchased these, I was a 36D. Now I am a 42DDD. My first pair weren't really long enough, and now I have to be careful when I am wearing these not to let my breasts move away from each other at all otherwise they pull one off because the chain isn't long enough.

They will be amazing for a C cup or smaller. Larger women can still use these, obviously as I have had 3 sets, but if you are larger, you will want to keep in mind that your breasts can pull these off.

BDSM?
I originally bought my first set of these as a compromise between my kinky self and a very vanilla partner. And they were perfect for that. Now that I am with some one who is kinky as well, these are not a toy that we would use together. Sure they can hurt a little, but in the end they are flimsy and easily fall off. Not the best tool for harder BDSM play.

Packaging and Storage
These come in a small plastic clam shell like the majority of sex toys do. You can easily see the product and the nude model on the front, so there is no way I would call this discreet.

Theoretically you can store them in the packaging, but nothing that they are made of required them to be kept separate from other types of materials. I keep them in a small box with my other nipple clamps on my nightstand.

Experience:
I have now owned 3 of these. This is because the quality isn't the best, but for the price I really can't complain because we get a ton of uses out of them. The first two broke in the exact same way. The rope used frays and becomes loose. This causes it to be difficult to loosen and too much force was exerted which pulled the knots out.

I obviously like these enough to continue buying them. I often use them in masturbation because that sensation will heighten my orgasm, and I still use them with my vanilla partner.

I feel that the price of these is worth the cons that they have, but they won't work for everyone, and I do not consider these beyond a light play BDSM toy.

I still like this. They aren't my favorite nipple toys, but they are really nice when I am having a very sensitive days. I like that they are light weight because they aren't solid metal like other clamps. These are still cheap and won't work for everyone, but I have always liked them.