I joke with my patients that a pessary is like a diaphragm on steroids. A pessary is slightly bigger and stronger than a diaphragm so it can support the prolapsing vaginal tissues. Some descriptions of pessaries date back to 1500 BC and some consider it one of the oldest medical devices invented.
Needless to say pessaries work or else they would not continue to be in use. Modern pessaries come in various shapes and sizes. They require proper fitting for comfort and effective use. I tell patients that getting a good, properly fitting pessary is like getting a good pair of shoes. One must try several on, walk around, squat, and sit to insure that the pessary will not slip out while in use and that it is comfortable. A pessary should be easy to place and not felt while in use. When a pessary is in place you should not have to think about it, or the prolapse, so you can get on with the activities you want to do.