The Endurance clamp is a non-adjustable clamp set with rubber covering the metal ends. It is more for an experienced user, and if you are really into it, then you can use them without the rubber. But for me, there was no way I was going to use them without the rubber. The ends are just clamps that do not adjust in any way, so if it's too uncomfortable, you can not adjust it.

It took me a while to figure out how to get these clamps to stay on my nipples, since I have larger nipples. The clips are pretty strong, and I found that I had to bend them open a bit extra to actually enjoy them. I did have to play around with my nipples (since they are not as perky as most women) to get them harder, so that it was easier to get them to stay on.

The endurance clamps are made of metal and weigh in at 1.7 oz, which is pretty lightweight for being metal. They are 16" in length from one end to the other end of the clamp. They have no reason to be cleaned unless you get lube or something on them from sex play. If they do need to be cleaned, I just use warm water and soap and make sure they are completely dry before storing them. For storage, I just let them be loose in my toy bag, since they do not collect hair or anything.

These are purely MADE for pain! If you do not know your body well enough to know your pain tolerance level, do not use them! Go for something that can be adjusted (like the tweezer style). These were made for advanced level of users, like me. I can tolerate pain really well, and can wear them up to an hour and sometimes a little bit longer than that. Mainly they are just worn for sex, but they are great for me.