Yes. Coldcard MK4 can be powered by a separate USB power adapter, power bank, or COLDPOWER, while files are transferred using a MicroSD card. In this setup, there is no need to connect the device to a computer with a data cable.

A watch-only wallet creates the PSBT, the file is transferred to the MicroSD card, signed on the Coldcard, and then returned to the wallet for broadcasting to the Bitcoin network.

PSBT stands for Partially Signed Bitcoin Transaction. It contains the information Coldcard needs to review and sign a transaction without exposing the private key.

With PSBT, you can create a transaction on a computer using a watch-only wallet, transfer it to Coldcard via MicroSD or another supported method, review it on the device screen, and sign it in an isolated environment.

A MicroSD card is used for the traditional air-gapped workflow: exporting a watch-only wallet, transferring PSBT files, saving signed transactions, creating backups, and updating firmware without a USB data connection to a computer.

The MK4 can also be used via USB-C, NFC, or USB Virtual Disk Mode. A MicroSD card is not included in the standard package and must be purchased separately. Cards up to 32 GB formatted as FAT12 or FAT32 are supported.

Two Secure Elements from different manufacturers store and protect the wallet’s critical secrets. This architecture reduces reliance on a single security chip and makes physical attacks more difficult.

Compromising the keys requires more than finding a vulnerability in just one component, because the security model also involves the second Secure Element and the main microcontroller.

The Coldcard MK4 PIN is divided into two parts. After you enter the first part, the device displays two unique words. During the initial setup, you should memorize these words and verify them before entering the second part of the PIN in the future.

If the words do not match, do not continue entering your PIN. It may indicate that you are using a different or modified device.

Trick PINs are additional PIN codes that can trigger different actions. Depending on how they are configured, they can open a duress wallet, introduce a login delay, delete the seed, or lock the Secure Element.

These are advanced features intended for experienced users. Before enabling them, carefully read the documentation and verify that you have a working backup of your seed phrase, as some actions cannot be reversed.

NFC on Coldcard MK4 is disabled by default and can only be enabled by the user. It operates over a very short range and can transfer PSBTs, addresses, XPUBs, and signed transactions to a compatible smartphone.

If you do not plan to use NFC, you can simply leave it disabled. The board also provides an option to physically and permanently disable the NFC circuit.

Coldcard MK4 is compatible with Sparrow Wallet, Electrum, Nunchuk, Specter Desktop, Wasabi Wallet, BlueWallet, and other Bitcoin wallets and tools.

Available connection methods depend on the specific application. The most common air-gapped setup uses Sparrow Wallet or Electrum with PSBT files transferred via MicroSD.

No. Coldcard MK4 does not have a built-in battery and requires external power through USB-C.

For air-gapped use, the device can be powered by a standard wall adapter, power bank, a dedicated power-only cable, or COLDPOWER with a battery. USB data transfer is not required.

A new Coldcard is shipped in a factory tamper-evident bag with a unique number. Before opening it, inspect the bag for damage, signs of resealing, or any other evidence of tampering.

During the first startup, the bag number should be compared with the number stored in the device’s protected memory. If the numbers do not match or the packaging looks suspicious, do not generate a seed phrase or use the device.

A hardware wallet keeps your private keys separate from your phone, computer, and online services. Even if the connected computer or phone is infected with malware, the transaction still needs to be reviewed and confirmed on the hardware wallet itself.

Coldcard MK4 also allows transactions to be signed without a direct connection to a computer by using PSBT files and a MicroSD card.

LWallet.com.ua is a Ukrainian online store specializing in hardware wallets, security devices, seed phrase backup solutions, and accessories.

We offer a wide range of devices, deliver orders throughout Ukraine, and help customers with setup. In addition to selling hardware, we provide guidance on secure asset storage. All products are covered by warranty, and we work only with original devices.

We provide the manufacturer’s warranty and will replace any defective device within one year.

We can help you set up the device in our office or remotely. If you have any questions about your hardware wallet, we can assist you by phone or via Zoom.

We deliver to any city of Ukraine. During checkout, you can choose a convenient branch or pickup point.

Yes. You can pay the courier or pay at the pickup point when you receive your order. Prepayment by bank transfer is also available.

Yes. We sell original products only. A new Coldcard MK4 is supplied in a factory tamper-evident bag with a unique number that is verified during the initial setup.

You can view the Coldcard MK4 on the manufacturer’s official website, but availability from Coinkite may change because newer devices are already part of the current product lineup.

When ordering from abroad, you also need to account for international shipping, delivery times, and handling warranty claims directly with the manufacturer. We usually ship orders on the same day and provide assistance with setup and warranty service.
Go to the manufacturer’s website