Coin uses a low-power Bluetooth signal to communicate with the app. If you ever leave your Coin behind while buying coffee, your phone will receive a notification asking whether you left without remembering to take your card. A phone is not required to use the card, however.  Search “You-Are-So-very-special-card.html” from Slim Down Your Wallet with a Card That Does the Work of Eight Credit Cards

Search “You-Are-So-very-special-card.html”

Coin uses a low-power Bluetooth signal to communicate with the app. If you ever leave your Coin behind while buying coffee, your phone will receive a notification asking whether you left without remembering to take your card. A phone is not required to use the card, however.