It's a hardware signer on an NFC card. You just assign your wallet key to the Tapsigner, and you'll be required to tap it on your phone to sign your send transactions. It basically moves the key to the card. It's very similar to other hardware wallets, but the configuration is done in your wallet app, and there's no interactivity other than tapping it when you're sending a transaction. And it's only $20 so you can get a few of them for signing multi-sig transactions.