These are two attached duotone balls. Duotone balls are different from ben wa balls in that they have another, smaller ball inside the outer ball which is weighted, so that it moves around inside creating a rattling type sensation. They basically work by making your muscles work to keep them in place inside of you. They are not so much better than doing kegels, but all you have to do is put them in when you wake up as part of your morning routine and leave them in for a few hours a day, as opposed to remembering to do your kegel exercises. They remember for you!

These balls are about 1 7/8 inches across, and there are two balls. They are attached by a nylon string between them and a string on the end that hangs out for easy retrieval (think tampon string). The balls themselves are made out of plastic and are obviously each made out of two separate pieces, as there is an obvious seam all the way around both of them. You can even see this seam in the product photo on the main page. From what I have read in the other reviews, some people are able to feel this seam inside of them, but once they were in I did not notice it at all. You should clean these with hot soapy water every time after you use them, and before you put them in as well. As you can imagine, the string does not clean up very easily and therefore I would only recommend reusing these so many times. I would not consider these a long term investment like a glass, metal or silicone set. However, if you are unsure if you will be able to retrieve them after use, or if you are unsure about the idea of using them all together, these are a great starter set. That is why I got them.

These were more than large enough for me. They were easy to put in with a little bit of maneuvering, and simple to pull out. They are comfortable and, to be honest, I forgot they were in from time to time. The first time I wore them they were very noticeable, making me feel a little full, but once they have been in for a while, the sensation faded a little. I did not seem to feel the vibration sensation as much as I would like from the inner balls moving when I walk, but I could hear them when the house was quiet (my husband could not). These are strictly for vaginal use, as there is nothing that would keep them from "getting lost" in your ass. I suppose, if you trusted the string and left one ball out and put one in, that might be safe though.

These have ended up in the trash and being replaced by a pair of smoother and more sanitary glass balls.