It is a wallet that can be used offline and the private key is saved in the offline computers, smart phones and other devices. Because the private key can’t be accessed by the Internet， it is the safest way to manage assets so far. large amount of assets are strongly recommended to be managed with cold wallet.
You need to prepare two phones. The one is used to install ZebraColdWallet and keep it under airplane modehe. The another is used to install ZebraWallet and wathch cold wallet.