Dimension: 9cm x 5cm x 0.5cm
Coldcard is a Bitcoin hardware Wallet, it signs transactions and can be used offline.
Easy to use
BIP39 based, which means you can backup the secret words onto paper, and have lots of sub-accounts and unlimited independent payment addresses. It knows how to understand transactions, so you can see what you are approving. The first psbt (Bip 174) native Wallet which can be used completely offline for its entire lifecycle.
Secure element and open source
Physical Security. Your seed words are stored in a specialized chip, designed to securely store secrets. All code is open source, and you can compile it yourself.
True air-gap operation
Only hardware wallet with the option to never be connected to a computer, for full operation: from seed generation to transaction signing.
Uses PSBT (BIP174) natively