It also enables the phone to appear thinner than it actually is, as well as housing a lot of extra battery power. (techradar.com)
This iPhone case provides 100 % + extra battery power for those times when you can't get to an outlet. (ordinarytraveler.com)
LG says not only does the neckband provide extra battery power and vibration alerts for incoming calls and text messages, it also provides a secure place to store the earbuds when not in your ears, making them less likely to lose. (indianexpress.com)