The key is made by a company called Feitian (Feitian Technologies Co., Ltd), on Amazon. That's the original manufacturer selling directly on Amazon [1]. That's the only one available. Its about as authentic as you can get on Amazon. I'd rather buy it from Gearbest or Banggood but they don't sell this. And Google just sells it rebranded.

Though I won't buy this (I could use the BLE part of it), since for one it doesn't seem to be build strongly (overcome-able but still), it only seems to work with Chrome according to reviews (I use Firefox), and I'm unsure if Bluetooth is secure for this method, nor reliable. NFC should be fine, since its much closer range, and I have a YubiKey NEO but my phone doesn't have NFC, unfortunately.

[1] https://www.amazon.com/Feitian-MultiPass-FIDO-Security-Key/d...