Solid 2FA I have been using the YubiKey for over 2 years now and it has saved me and my company from potential damage on multiple occasions. Just make sure to never lose your key ;)

This is the 3rd key from this company, what a nightmare This is the 3rd key from this company. It was simple enough at first but since buying one for my Android phone via USB-C it's been an hour now and I still can't work out how to register this and copy my sign-ins over from my other keys. Why can't they make it easier like cassette to cassette copying? remember that anyone? Why not have a one-click or two program that copies one key to the other instead of a load of complicated instructions? Beam me up Scottie.

Using Yubikey introduces the risk of the rightful owner of account is prevented access. It is a problem that Yubikeys cannot be duplicated for backup. They are so secure that even the owner of an account can be locked out, lol. That's not good. In case of lost key or hardware malfunction there is no way to access your account. Unfortunatly two different keys often cannot be registered for the same access. Using Yubikey introduces the risk of the rightful owner of account is prevented access.

I purchased 2 yubikey devices in May I purchased 2 yubikey devices in May, paid for express delivery, and still waiting for the devices to arrive at mine. I have tried to contact them via tweeter and emails but no headway so far

Their product didn't work Their product didn't work. Customer service offered a partial refund (excluding shipping costs). That's unheard of. When a product is returned, all payments are refunded and some will even send the client a free shipping label. When a product is faulty, that's goes without saying.