Packaging
The packaging is.... underwhelming; just a clear plastic bag and a label. You'll definitely want another bag to store these in for the long term or to give them as a gift. There also aren't any directions in there.

Materials and Design
The materials that make up these nipple clamps are really sort of a mystery because they aren't actually listed on the packaging or the products themselves. Those with metal or latex allergies might want to avoid them for safety purposes.

The metal is a typical shiny silver that unfortunately gets fingerprints rather easily. The ends of the clamps are covered in a rubbery black material that somewhat softens the intensity of the clamp. The rubber material could easily be removed for those who would prefer it. There is a ten inch long chain connecting the clamps. The chain is made of interconnected metal rings.

The clamps seem rather sturdy and have survived repeated use with not ill effects.

Use
These clamps can get as tight as most people would want. I have very sensitive nipples and no matter how much I enjoy pain I couldn't tough out the tightest setting. Luckily the clamps have a wide range of settings from very loose to painfully tight so everyone should be able to find one that works for them.

The unfortunate thing is how difficult it is to actually adjust these clamps. They operate with a screw that must be screwed in or out to adjust tightness. The head of the screw has a slightly textured knob that doesn't really allow you to get a good grip for turning. In the heat of the act it is nearly impossible to adjust them yourself and even with help it can be difficult. The best way to adjust the clamps is to remove them from the nipples entirely, which can somewhat kill the mood.

It can also be difficult to keep the clamps on in the first place. The rubber material at the end of the clamps causes them to slide off easily, especially when it becomes slick with sweat. Taking off the rubber doesn't solve the problem for me because produces pain too intense for my sensitive nipples. For these same reasons it is difficult to use these clamps on the clitoris.

Despite these downsides the clamps can really be quite fun. My favorite part is the middle chain connecting the two clamps. Pulling on the chain produces a very pleasurable sensation (as long as the clamps stay on).