What is Coin, you might ask?
Coin is a credit card-sized device that digitally stores up to eight credit, debit, gift, or membership cards, and lets you switch between them by pressing a circular button on its surface. You can then swipe the Coin in any conventional reader or ATM machine as if it were the original card itself.
Coin works using a patent-pending magnetic strip that changes on demand. The device ships with a small reader you use to scan cards into the Coin mobile app, which then syncs with the device itself over Bluetooth Low Energy (BLE), the same power-sipping protocol used by many fitness trackers and smartwatches. Coin’s battery lasts two years, the company says, and powers a tiny display that shows the last four digits of the card you’ve currently chosen to use, as well as its expiration date and CVV. Since Coin stays in constant contact with your phone using the same BLE tech that powers syncing with a phone, if you leave it behind at a restaurant, your phone will alert you once you walk away.