The LoopPay system comes with two devices: the ChargeCase, which has a magnetic loop that works with credit card terminals, and a separate Fob that scans your credit cards and can be used as a second way to make credit card payments, too.
Press a button on the side of the ChargeCase, and you can make an instant payment with a scanned-in default card. You can also tell the case to turn off payments after just a few minutes, or several hours.
The LoopPay Fob plugs into the headphone jack like a Square credit-card reader. It has its own battery and can be separately authorized to make payments. It's sold separately for $39, and works with both Android and iOS.