They work kind of...
EDIT: These literally shattered my Massdrop plus iems when inserted a second time.
So I had bought these originally for my edc3 in hopes that I could enjoy the iems that I already loved wirelessly. I had already known going into this purchase that since the edc series of iems have a two pin connector that has a sleeve over it for stability that I would be missing out on the additional security and durability of the oem cables. I never had an issue with the pins falling out of either of these iems but, the additional length that the cable protruded out of the connectors, due to the pins on the BTN being designed for recessed connectors, made wearing the iems over longer periods uncomfortable. The BTN fits wonderfully in my Massdrop Plus.
Now as to why I'm giving this product a two star rating. First off the connection stability is pretty terrible. when inside of a building the connection seems fine but I have noticed that when walking between buildings at my school that the connection constantly cuts out. I am wearing these in the correct way with the strap behind my head and my phone in my front right pocket. Reason number two that I don't love the BTN is its noise floor and its overall sound. With the original dynamic driver edc this cable sounds good. I have no complaints in using it with that iem. With the edc3 there is a noticeable amount of hiss in the background all of the time but otherwise these also sound fine with the BTN. However with the Massdrop Plus iem, the background is extremely hiss prone and crackly. When playing music it sounds screechy and just outright terrible. I cannot under any circumstances recommend that anybody use the BTN with the Massdrop Plus. The last reason that I don't love these is the battery life and charging method. First off, why isn't usb type c the chosen connector for charging? Micro usb sucked when it came out and it is no better now. With that said, this wouldn't be such a huge deal if the battery life wasn't kind of terrible. On average I get about 6-8 hours of total listening when using these with the edc3. I listen at very low volume levels so I am not using a ton of power but even so I can barely sometimes get two days of usage out of the BTN without having to recharge it. Using a cheap pair of tws earbuds from Enacfire or even when I had the Drop+Nuforce Move, the battery would easily last me 6-8 hours before I needed to pop the earbuds back into their case to give them an additional 3-4 times the amount of runtime. To top it all off, the battery percentage in android doesn't correlate to the actual batter percentage left. At about 30 percent battery the BTN will call out that it is on low battery, then I will get about 5 more minutes of playback, and then the BTN will abruptly shut off without a sound.
If you want to enjoy your existing .78mm iems wirelessly, I recommend either using something like Fiio's btr3, btr1k, ubtr, radsones es100 mk2, or something like these and just coiling up the cable or running the cable down your shirt. If you can settle for getting a new pair of tws earbuds then Enacfire's e18 plus and F1 are awesome and affordable though bass heavy (the e60's also look promising). At a higher price point, Sennheiser has their momentum lineup, and apple has their ever so popular airpods and airpod pros and I would unfortunately recommend all of these solutions before recommending the BTN.
Would not recommend to a friend.