It also comes with a USB-C charging cable, travel pouch, keychain holder, quick-start guide, and a manual.
Promising review:"I love this gadget ... I fly a lot and this works on the majority of wide-body planes I’ve taken over the past six months. Just plugs into one of the three-prong outlets (or single outlet in economy) and you can connect any Bluetooth device. Doesn’t always connect on the first try as I have multiple devices that my headphones are searching for, but if you turn off all other devices it seems to connect right away. Once connected, it works for many hours. A few planes I’ve taken recently (Qatar Airways) have USB charge points so close to the headphone jack that you can even plug it in while its working and never lose the charge. Highly recommend for travelers." —Joseph Sikorsky
Get it from Amazon for $30.17+ (available in five styles).