It's a smartphone app that embeds your private keys onto a near field communication tag. The only drawback is, it's android only. However, it is by nature the most secure way to store cryptocurrency as NFC tags never interact with the internet at all. The security is comparable to a ledger nano except at 40x less cost, and except it's more secure than a ledger nano because
NFC tags don't contain software,
and are immune to man in the middle attacks. They are also weatherproof and water proof, and highly durable (unlike paper wallets) and I'm selling them at only $2.50. The NFC tags can look like anything, don't require batteries or USB interface. All you have to do is keep up with the tag itself. When you want to transfer money you need both the APP and the TAG, but not necessarily your smartphone. It can be any smartphone with an NFC controller and the app installed
The app is free though I might make a pro version for 1.99. I'm not totally done but I plan on making a thread when I am.