I had had a very hard time getting the Zero:2 to fit my ears consistently, despite having tried at least 10-15 different types of tips. I found this was mostly due to these IEMs having such a short nozzle. Even using o-rings wasn't helping because due to the nozzle being so short, using o-rings would cause pretty much any tip to fall off too easily, in my ear. I was about to give up on these, completely, until I ordered the new AZLA Origin tips. I ordered the pack of assorted sizes, as one of my ears usually requires a different size tip than the other (with the exception of the extremely deep insertion fit of my Etymotics), and these tips finally work for me with the Zero:2!! I'm sure they can be ordered from multiple places, but here is a link to where I got them. They aren't exactly the cheapest tips around, but I've had multiple tips from AZLA before, and they have lasted me for quite a while, and have helped me attain a decent seal with other hard-to-fit IEMs in the past, so I found them to be worth it. YMMV