This is a pair of keys (Apple requires two of them to secure your Apple ID so you have a backup). Keys are in-hand and ready to ship (they are hard to come by since Apple recommended them as the #1 option for securing Apple IDs in iOS 16.3 and macOS 13.2).  See: https://support.apple.com/en-us/HT213154

The YubiKey 5C NFC is a hardware based authentication solution that provides superior defense against phishing, eliminates account takeovers, and enables compliance requirements for strong authentication.

The YubiKey offers superior security by combining hardware-based authentication and public key cryptography to effectively defend against phishing attacks and eliminate account takeovers. It offers multi-protocol support including FIDO2, Yubico OTP, OATH HOTP, U2F, PIV, and Open PGP. Users have the broadest options for strong authentication including not only two-factor authentication, but also support for single factor passwordless login and multi-factor authentication in conjunction with user touch and PIN.