The word "endurance" in the name of these clamps is not a joke. They are very intense and to endure them for any length of time you will need a high pain threshold level, or build up to one. I can handle them for about 5 to 10 minutes, but to me it isn't a pleasurable biting pain like I get from other nipple clamps, it is more of a "please make this go away" kind of pain. They are not adjustable and I really wish they were. I could use them much more often if I could control the intensity.

They are very well made and don't look cheap in the least. The chain is sturdy as well as attractive. As far as nipple clamps go these look very sexy in use. They aren't overly bulky nor are they too delicate. The metal with black accents look beautiful against your breasts (male or female). They aren't as elegant as some clamps, but I consider them more attractive than most nipple clamps.

I have many different types of nipple clamps and these are the ones I use the least simply because they are too strong and painful. They are much more painful on me than my butterfly/clover clamps (which are known to be very intense). With this being said, I still like them. Yes they hurt, but it helps me to build up my pain tolerance even if I only use them once in a while. Since I can't use them on a regular basis, I have found other uses for them. Most often I use them to add a chain to a set of clamps that don't have a chain. I just clamp them on the bottom of each individual clamp and then I have a nice thick chain to pull on, twist, add additional weight to, etc. to give me more "bite" with clamps that that aren't as intense as I would like them to be.

It has been two months since I wrote my initial review. I am still using and enjoying my "endurance clamps." I turn to them more often than many of my other clamps and this is because they fit me much better. They open up wider than many clamps and there is plenty of space to fill the nipple. I have larger than average nipples and have found that many nipple clamps are just not meant for nipples are large as mine (a little less than 1/2 inch wide and a bit longer than the width). The "endurance clamps" when opened up completely fit nicely over my nipples.

Also, because of their intense grip they are perfectly suited to add weights to (if that is your thing). They have not slipped off of my nipples yet... I don't even think they budged at all. The intensity of the grip along with the rubber coating keep them nice and stable on your nipple.

I want to reiterate that these clamps are not for beginners. They have a VERY strong grip and are not adjustable. But for those of us that like a bit more "bite" then these may be just what you are looking for.