For most phones the model number can be found on the barcode label under the battery.
For iPhones, the model number can be found in the small print on the back of the phone which can be checked against the list below. You can check the capacity of your iPhone under Settings>General>Storage & iCloud Usage.
A1332, A1349: iPhone 4
A1387: iPhone 4S
A1428, A1429: iPhone 5
A1456, A1507, A1526, A1529, or A1532: iPhone 5c
A1453, A1457, A1528, A1530, or A1533: iPhone 5s
A1549, A1586, or A1589: iPhone 6
A1522, A1524, or A1593: iPhone 6 Plus
A1633 or A1688: iPhone 6s
A1634 or A1687: iPhone 6s Plus
A1723, A1662 or A1724: iPhone SE
A1660, A1778 or A1779: iPhone 7
A1661, A1784 or A1785: iPhone 7 Plus
If you need further help identifying your phone model, please feel free to contact us.