Spartacus' leather nipple clamps are rather basic clamps, used to apply constant pressure to one or both nipples. Unlike a number of other clamps, these are not adjustable and pretty much have one pressure setting. The all-or-nothing nature of these clamps may seem like a weakness, but the inclusion of a leather cord allows for the user or a partner to tug on the clamps, eliciting new and potentially exciting sensations.

These clamps are a good, basic place to start, though one should be sure that they like their nipples being pinched rather strongly. While they are not the strongest clamps on the market, they do pack a punch, as they are essentially coated alligator clips... Bear that in mind when purchasing!

To use these, ensure that they are clean and that the coated tips are free of debris that may cause nipple irritation. Application is simple; just squeeze the open end of the clamps which are attached to the leather cord to open the business end. Place them around your nipples and gently, slowly release pressure on the other end, clamping them down on your nipples.

These clamps can be used in the bedroom, or if you so desire, discreetly under clothing. They aren't terribly large, so they should remain hidden under loosely layered clothing. One could even tug on the leather cord secretly if they wished to.

As I said above, these are pretty much metal alligator clips that have been modified into nipple clamps by the application of a smooth rubber coating; a sturdy leather cord has been attached to the operative end of each clamp.
The rubber coating has no noticeable smell or taste to me, nor does the metal portion.
I've personally found the rubber tips to be adequate in preventing too much pain from the metal clamp beneath, though they do not adhere to the clamps as I expected, falling off quite easily.

The shape of these is fairly simple; again, it's essentially an alligator clip. The design of the clip allows for nice pressure to be applied when in use, and I have had no issues with the durability of the metal portion. I would have preferred a slightly larger clip, however, as my nipples seem to be larger than I thought they were in comparison to the clamp. Your mileage may vary, however. Especially large nipples may have problems with this toy, but small- to average-sized nipples will be fine.

I find that they simplistic design of the clips make for simple application. However, I would have liked an adjustable clamp, such as a bull-nose, for added variety of pressure. I felt that the pressure was strong enough for my liking; not quite the same as, say, a plastic clothes-pin, but stronger than moderate pinching with fingers.

The rubber tips are comfortable, and cover enough of the clips to prevent injury from the underlying metal, but they really need to be glued on as they fall off easily when not in use.
The leather cord is roughly 12" long, an adequate length for the purposes of the product. It's quite fun to tug on the cord for extra stimulation!

As stated above, these clamps are pretty simple in their function, having close to no pressure variation, but gaining ease and quickness of use in the process. They do what they're supposed to do, and manage to stay where you put them in most normal situations. I found them to work nicely, especially for the price.

I would like to add to this section some precautions:

While you should enjoy yourself while using this toy, be sure to keep an eye on your nipples. If they become darkened or cool to the touch, release the clamps and take a break, as circulation can be impaired by the pressure of the clamps. It's a good idea to take a break after fifteen minutes or so, or sooner if you feel (unwanted) discomfort.

Be sure not to get the cord accidentally caught in something during use, as you can cause considerable injury to your nipples.

Also, make sure the rubber grips are securely placed over the business end of the clamps: the underlying metal portion is capable of causing quite a bit of injury.

Cleaning of this product is fairly simple. They generally have no exposure to body fluids, so cleaning need not be at the level of autoclave and bleach. For peace of mind, you may wipe the rubber clamp portion with an alcohol swab and allow to dry, or remove them and wash them in warm soapy water (being sure to keep the sink plugged, as they're pretty tiny). I would avoid getting the metal and leather parts wet if possible, but if the metal does get wet, it should still dry adequately if left open to air. I wouldn't store them without ensuring that they are dry.

Storage is a snap; they're pretty small, so they can fit in any bedside table, toy box, etc. You could keep the packaging for storage, but it's not ideal.

These clamps come packaged in a minimal clear plastic clamshell with a cardboard insert. This container is not ideal for storage, nor is it very discreet. Not only does it display its contents clearly (which is great for a shop display), but the packaging clearly states "nipple clamps", and features a perceptibly nude woman on the insert (though nothing explicit is being shown). As a result, if you're giving these as a gift, do so in private as it could be embarrassing otherwise.

I'm afraid my first impression of these clamps was not as positive as I'd hoped. I removed them from the package, and without even touching it, one of the rubber coatings fell off! Granted, it wasn't torn or broken, it was just loose, and could be easily placed back where it belonged... Still, I'd hoped the coating would be well-adhered to the material. One could glue them on if they wanted to, of course.

I liked the design overall, however I do wish that these were adjustable... And a little bigger.

As for using them, I had a bit of trouble getting them on due to the (seemingly) large size of my nipples, but I did have success within a few minutes. They felt quite nice, though I learned that I prefer suction (such as that of Supple Nipps) to pinching when it comes to my nipples. That being said, these are a nice toy for someone who wants to experiment with clamps; the price is quite reasonable as well.