A1920: which Apple model is it?

Model number A1920

Check the number on your device

In Settings

Open Settings, then tap General.
Tap About.
Next to Model Number you first see the part number. Tap it to see the model number.

On the device

iPhone 7 or earlier: the model number is on the back.
iPhone 8 or later with a SIM tray: remove the SIM tray and look in the slot. The number is on the upper side, the side with the display. Use bright light overhead.
iPhone without a SIM tray: look inside the USB-C or Lightning connector, on the upper side (the side with the display). Use bright light overhead.