If they are the right size, triple flanges offer the most ambient sound isolation, on par with silicone custom molded In-Ear-Monitors. I've tried every single brand name model that I could find, including two different models by Shure (one of which long discontinued), a long discontinued Westone model and the gray and clear models sold here by Etymotic. They are all similar in size and and they all look nearly identical, but the properties of the silicone is different. The absolute best ones by far are the Etymotic clear model (ER38-18CLL). They are comfortable the first time they are used and stay comfortable after many hours of use (although it can take some time to get used to them if never used before), a single pair lasts literally forever (my job allows me to wear them all day long and my estimation is thousands of hours) and they provide an excellent ambient sound isolation that's retained throughout their whole lifetime. No other triple flange model that I've used comes even close, especially in all three categories (comfort, durability and isolation).