This review is based on my experience with these tips on the Shure SE846 IEMs. I have owned the 846s for 5 or 6 years and it seems that I have been on a constant search for eartips. Silicone or foam? Single, double or triple flange? Foam is comfortable but silicone is durable... What do I do? Well a few years ago I discovered SpinFit and tried the CP240. They are as comfortable as foam but as durable as silicone. I can wear them for hours without fatigue. When it comes to getting a good seal on the Shures the CP240s are second to none. They have far and away the best noise isolation of any eartips that I have tried over the years. If you are constantly in noisy environments these are the tips for you. They sound great!. Bass is tight and low without getting overwhelming. Mids and vocals are forward and crisp. Highs are excellent but not as crisp as, say the SpinFit CP100+. Until I found the CP100+ these were my favorite, goto tips and they are still always with me in backpack in case I need more isolation than the CP100+ offers. They surface of the tips are rough so they stay in place. Over time they do wear and become slick so they have to be adjust more often. This happens very slowly so you really don't notice until you replace them. I end up replacing mine about once every 12-14 months. I am on my 4th set so they are so good that I keep buying them. The only thing that I would like to see is for SpinFit to upgrade them to the medical grade silicone like their other products vs the current food grade.