https://www.theverge.com/circuitbreaker/2018/9/11/17845778/google-headphone-jack-dongle-update-price-increase

Google is now selling an updated headphone adapter that’s supposed to be more responsive and less of a drain on battery life. Physically, though, the dongle is nearly identical to the USB-C to 3.5mm adapter that Google has been selling since last October: this new version is just a hair smaller in almost every dimension.

But on the inside, there are apparently some very minor changes. Google says the new dongle will connect to your phone ever so slightly faster, and, more importantly, it’s supposed to draw less power, translating to 38 percent more playback time. The update was first spotted by Android Police.