Model Number

The first letter in the model number represents the source of the device. Currently, there are four known possible choices:

• "F": refurbished unit
• "M": retail unit New
• "N": replacement unit
• "P": personalized (engraved) unit

The unique model code of an iPhone is the one with this structure "Axxxx" (where xxxx are four numbers), and is obtained by double-tapping the field in Settings>General>About>Model Number.

See this support article:--> Identify your iPhone model

That said, see this useful article:--> https://www.theiphonewiki.com/wiki/Models (search your model in the list scrolling down to iPhone section)

Regards

Giulio

My pleasure :)