AirGap is a secure mobile wallet with 2 apps. The AirGap Vault allows you to securely generate and store private keys and should be installed on a phone with no connectivity. The AirGap Wallet app is installed on your everyday-phone. You can use it to check your portfolio and initiate transactions, which then need to be signed with the Vault app.
AirGap.it makes air-gapped cold storage infinitely more usable with a mobile app.