Great, but pay attention to bore sizing.
Ok, so I'm not sure if I just wasn't paying enough attention when I was setting up my order, but it's important to understand that these tips come in two different bore sizes: 3mm (Gemini), and 4.9mm (Mercury). Makes perfect sense that they would, but I just don't recall seeing the option to choose between those when I was ordering.. I ended up with the Geminis, which are way too small to fit my earbuds. So don't be like me; pay attention!! (Dekoni provides fitment charts on their website, FYI)
I was eventually able to get them to fit by removing the stiff blue rubber that is used to size the bore down to 3mm, but it was not easy to do -- these are really well made, and I can certify that the foam Dekoni uses is _very_ high quality to withstand what I put them through in order to get that stuff out.
Now that they're in place, these are excellent tips, IMO. I'm using them to replace the stock blue tips that came with my Tin T2s, and they are not only much more comfortable, but they stay in place a lot better, resisting the occasional tug on the cable far better than the Tin tips did (my main reason for looking at other options). Sound-quality is excellent as well; they seem to be sealing better than the stock tips, so I'm getting better isolation and more presence to the sound in general.
Highly recommend, just be sure you're getting the right size!
Would recommend to a friend.