These balls are inserted into the vagina, and are intended to be left there for sequentially longer intervals (20 to 30 minutes a day, for 6-12 weeks). They are meant to strengthen your PC muscles by forcing contractions due to their weight and movement. They are like ben-wa balls in that the have an inner ball that rumbles around causing them vibrate subtly. These little guys (each being slightly smaller than a golf ball) were very enjoyable during use, and we both felt a difference almost immediately in the tightness felt during intercourse.

They're constructed of nonporous, phthalates free, hypo-allergenic, food-grade, latex free silicone (elastomed). They are very smooth; however they do have some ribs that swirl through them. Their size is big enough to insert but not too small where they feel like they may come loose. They are made by Fun Factory, a German company known for their quality in construction and research. They seem extremely durable and I cannot imagine any wear and tear issues.

Smart Balls come in a variety of colors, there is no variety in size.

They have a loop to pull on for removal, and come out as easily as they went in. It's been recommended to use a slight amount of lubrication, but be stingy, as they may want to come out with too much.

These balls are also touted for incontinence, I have no such problems, but as they definitely impact the PC muscles, it's easy to see how that could affect incontinence issues arising from weak PC muscles.

Smart balls are super silent and when inserted cannot be heard at all. The only way any would know you were wearing them would be the smile on your face. I ended up wearing them all day long, even though at most times I forgot I was wearing them.

These fit comfortably inside me, I read that you should insert one ball and then wait a moment for the next, but they inserted rather easily. They were very enjoyable and it got me in the mood for later activity. Stairs are an extra plus, so skip the elevator.

If we could stay more disciplined in using these it makes a difference. I still like them and they hold up well. Imitators seem to get bad reviews. I'm glad we went with fun factory smartballs.