After I set it aside for a couple of additional weeks, it mysteriously started working when I tried it again, and it’s been working great for many additional weeks now.

These work amazingly well

It has worked great for me on very long flights and days at work where I need "privacy

No jitter, super fast charge, automatically turns off when not in use, mini USB, microphone works fantastically for calls

I ended up returning these because my QC25 turned out to be defective (the right can had some issue), but if you have your lovely, good-working QC25 and don't want to spend a whole bunch on the new QC models, this will really enhance your listening experience by getting rid of the chord