The iPhone 5s fingerprint scanner is one of the device’s biggest draws, and customers checking out the new smartphone at Apple stores can expect to try out the new Touch ID feature before they buy the handset. To demo the fingerprint sensor, the company has reportedly developed a simplified app that walks customers through the process, and according to 9to5Mac‘s Mark Gurman, demo versions of the iPhone 5s will be on display at Apple stores around the world starting on Sept, 20.

The fingerprint scanner demo guides users through the new security feature on the iPhone 5s, though it doesn’t offer the full experience. After launching the app, potential customers will be directed to hold their finger on the Home Button while Touch ID scans their fingerprint. Users will then touch their finger to the sensor again to see a successful scan, and then hold a different finger to the button to see the red error message. As soon as the app is closed it will automatically reset for the next user.

Touch ID for the iPhone 5s works by using a built-in capacitive sensor that scans your finger’s sub-epidermal skin layers. The fingerprint sensor works at any orientation, and can save five different fingerprints at once. At launch, the technology will only allow users to unlock the device and make iTunes purchases, though it’s possible that Apple will open up the software to developers in the future.