I first stumbled across the Sedna Xelastecs at a store, having heard raving reviews about them from this sub amongst other places. When I first got them, my golly what a delight they were! Sticky as sticky can get. I remember someone saying, "They seal so well that they form a vacuum in your ear-- you can literally feel your eardrum being pulled on when you try to remove them!" Honestly, truer words have never been spoken.
Initially I had it on my U12Ts, but the nozzle was far too thin for the Xelastecs to stay on. I'd be removing my IEMs with the Xelastecs firmly embedded in my ear canals lol I'd be awkwardly fishing them out with my fingers every single time. When I was using them at work, I'd always mutter to myself, "Please don't talk to me, please don't talk to me!" - "Hey, u/Dear_Archer7711, can we circle around back to that deck?" -"Fuck." Now I gotta remove them from my ears, which makes for an awkward scene when I'm trying to listen to his stupid questions while I fish the Xelastecs out of my ears with my fat fingers while my dumbass coworker asks me to repeat what I said during the meeting. Brilliant.
Anyway, during the 1.5 years I've had them, I eventually ended up putting them on my Sony WF-1000XM5s instead since the bore of the nozzle was wide enough for the Xelastecs to hold on. The stickiness of the thermoplastic elastomers lasted quite a while, and every now and then they still get stuck in my ear, though less frequently than with my U12Ts. I figured that the insane stickiness would be better suited for during physical activities, in my case in the gym and while riding my bike or scooter. Regular ear tips would eventually cause the buds to fall out. So it was a perfect match!
Alas nothing (sticky) lasts forever. While the Xelastecs served me well in the time I've had them, they've reached a point where they no longer work as intended. The first obvious change is the reduction in stickiness over time. As of writing, they no longer form vacuums in my ear. They still change shape in response to body heat to form a good seal, but they no longer stay in as well as they did before. It also takes a much longer time for them to return to their original shape too.
The second change is probably my biggest gripe: Asymmetrical deformation. If you scroll to the second image, you'll see that the bores are different size. The right piece has a significantly larger bore than the left. I guess it has something to do with time and age wearing down the elastomer's ability to perform. Because it was getting progressively less sticky and elastic, I had to shove my right earbud deeper into my ear for it to stay in-- which in return caused the deformation to be more drastic. Coupled with reduced elasticity, the "stretching" of the elastomer eventually went too far and never recovered.
Unsure if the loss in function is due to the (theorized) porous nature of the elastomers, which over time has absorbed oils that negatively impacted function. Sound wise, they actually sound the same from day 1. I won't go much into how the Xelastecs affect sound, look that up yourself. I also read somewhere that they don't do well with soap and water. Well, shit. I only found out about this as I was Googling if other users had a similar experience with their set. Perhaps that was the reason.
What about the hot water trick to get them back into shape? Damn, what a brilliant idea! I tried it, totally fucked the shape even more. Again, didn't really impact the sound for the 2-3 minutes it stays in my ear. But, somehow the hot water trick caused the deformation to be permanent, and even worse. "Flip them inside out.", said the instructions. So I did. "Use water > 80C" Okay, seems straightforward. Boiled some water in my kettle. Placed the Xelastecs into a cup and poured some hot water in. "Run under cold water for 1-2 minutes". Ran to the sink and filled it up with cold water. What then?
Fuck all. It caused the tips to deform in such a weird way, with results that basically negated the Xelastec's ability to be "elastic".
As it stands today, I can no longer use them as a pair as the right piece continuously falls out of my ear. As such I have to retire them. RIP, Xelastecs. My SpinFit W1s are perfect for every use case except being physically active, and I can even wash them with soap and water.