Your computer prepares the transaction; the hardware wallet displays it, you verify the address and amount on its own screen, and it signs inside the device. Malware on the computer never sees the keys — that separation is the entire product.
Prices run $79–250. If you hold more bitcoin than you would carry as cash in your pocket, the device pays for itself the first time it prevents a mistake. Our ranked reviews cover
Coldcard,
Trezor, and
Ledger.