The Endurance Clamp is a non-adjustable, metal nipple clamp that contains a rubber-like cover over the clamp itself to provide a cushion between the metal and your nipple. While you can remove the rubber cover, I would recommend not doing so because the metal of the clamp has teeth-like ridges and can really do some harm to your nipples--and that isn't fun in the least!

The clamps are linked by a metal chain and while it isn't terribly long, it is long enough that it will hang in your partner's face if you're leaning over them. If you're wearing them for masturbation or foreplay alone; however, you shouldn't have a problem with the chain's length. I read in another review of these clamps that they were able to remove the chain all together, but it does not naturally lend itself to be taken off, unless you have a pair of pliers and can bend the metal, but please note that you will most likely be ruining the chain and won't be able to re-attach it later.

The clamps have a raised, textured grip so your thumb won't slip when you're trying to open and position them on your nipples. Because these clamps are not adjustable, I was a bit wary about them being able to fit correctly, not knowing exactly where my nipples fall in terms of size. Turns out, I have what are commonly referred to amongst crowds of mostly men as "door stop nipples"; nipples that are very large and when hard, they jut out very significantly. Because of this, I thought that no nipple clamp could have a hard time latching on since there is a great deal to latch on to. I was very sadly mistaken.

When I initially opened the clamp as wide as I could with the grip, it looked like it could accommodate a larger-sized nipple, but when trying to latch them on, I found it very difficult to get them on at all. After playing with them a little bit and trying to latch onto the front of my nipple, as well as on the side, I got it on and then it popped off after a second or two. After working with them a bit more, I got them to stay on, although they looked like they were going to pop off again. In the not very long amount of time I had these clamps on, I found them to be extremely painful, which surprised me because I really thought I had the endurance needed for the Endurance Clamp. I've had my nipples pierced before--if that doesn't show endurance and a tolerance for pain, what does? It is worth noting that I did not have any piercing in my nipples at the time of trying these nipple clamps out, so nothing was obstructing the way that they fit, bu it is a good barometer for measuring one's pain threshold.

The Endurance Clamp is not a nipple clamp for beginners to either S&M or to mixing a little physical pain with pleasure. I would recommend these clamps only to people who have had a vast amount of experience with products like them and are looking for something a lot more aggressive. All things considered, their $15 price tag is more than reasonable if you're feeling a little daring and think you have a significant tolerance to pain.

The Endurance Clamp was definitely not the right nipple clamp for me. I had a very hard time getting them on and when I finally succeeded in positioning them on my nipples correctly and could get them to stay in place, they provided more of an extremely painful sensation than anything else. I thought I had a high enough pain threshold for them and I have always loved intense and even painful nipple play, but these probably won't make it out of my toy box very often.