The BBPOS Chipper 2X BT is an older Bluetooth reader. It still works with the app, but it's no longer sold — newer readers like the Stripe Reader M2 have replaced it.
To use one, you'll need an iPhone, iPad, or Android device with Bluetooth running a current version of iOS or Android (whatever the latest Payment for Stripe app supports). If you're setting up in-person payments for the first time, we'd steer you to a current reader instead — see our list of supported readers.