Please follow the below steps to identify your iPhone size (model):
1. Open Settings
2. Tap your Apple ID profile at the top
3. Scroll down until you see the list of your devices.
4. The first device listed is your iPhone. You can see your iPhone size here (below the device name).
5. You can also tap on the device name and you'll see your iPhone size info (model), iOS version, serial number, etc.
6. Return to Bandolier Shop page.
7. Select your iPhone size and continue shopping!