I take it back. There aren’t any articles about the Pro Plugs that I could find. Here’s the deal. I had all kinds of trouble clearing my first year of diving. I averaged an ear infection or sinus infection every couple months. Very frustrating. Then I found Doc’s Pro Plugs (must be vented kind) at my local dive shop for $12. The shop had a sizing kit which allows you to try on different sizes to find the best fit. The theory is, as I understand it, the vent lets in water but does not allow it to flow in and out. There are two benefits. #1 your head warms up the water which makes for easier clearing. #2 the small amount of water in your ear canal limits the amount of bacteria your head is exposed to, reducing your chances of getting a bacteria infection. I swear I have not had a single infection in 4 years and 200+ dives since using these things. I know this is starting to sound like a commercial, but I really believe in them. My wife and many friends use them on every dive too. A great side benefit I just found it to use the same plugs at a concert. They don’t plug the sound, but instead they knock off the high end 15 decibels or so. I just went to a concert two weeks ago and for the first time ever my ears did not ring all night afterwards. Not a back return on my 12 bucks! :-)