This suction cup plug is made to be inserted into the vac-u-lock line of dildos. Once inserted, you have a convenient way to keep the dong in place when you want to insert it by sitting on, or backing up into it. Just wet the suction cup part lightly with water and stick it to a flat surface. I'm not sure if there are other uses for this other than with vac-u-lock dildos. It is pretty thin and made specifically to fit these lines of dildos. The suction cup ring is also probably a bit too small to try and use this with a harness ring.

The suction on this little thing is very powerful, much more than I was expecting. I was able to suction this to a wall while a Vac-u-lock realistic dong was attached. According to the manufacturer's data these dongs are 1 lb., not a small feat for this little suction cup plug to hold up sturdy. The realistic vac-u-lock dongs tend to fall over when you try and stand them up, so the ability to suction it steady to a surface made the toy a lot more usable.

This is more a slight against the Vac-u-lock realistic dong I used this with, but that line of dongs are very flexible. The plug provides no additional support or rigidity; it just allows you to hold it in place on a surface. The Vac-u-lock realistic dongs will still bend in a way that makes it difficult for insertion, making the ability to hold them firmly on a surface feel a bit pointless at times.

Once inserted into a dong, this plug is pretty hard to pull out. I suppose this is partly a good thing. I don't see any way this would accidentally come out of the dong while being used. However, when you actually want to remove it, it will take a decent amount of strength and dexterity to get out. I found that wiggling it from side to side while you pull made it slightly easier.

This plug is plastic, and while it likely won't come in contact with a lot of body fluids where it is positioned, it can be cleaned with a damp cloth and some antibacterial soap or cleaner.