They are awesome. They block out most noise by themselves anyway, so the ANC is just an added bonus. Comfortable, too. It's what I've had on my Hammerhead BTs since day 1. Yeah, but it's not expensive to get replace from Comply themselves, and the difference in isolation between silicon and foam is like night and day. I even use them at work as earplugs (and a good excuse to be secretly listening to music at work) because the isolation is so good.