Do you know what Sim-Card you need for your iPhone?

All iPhone models — with the exception of the iPhone 4 (CDMA) (A1349) — use SIM cards, but the type varies between models. 

Specifically, the iPhone models use these SIM card types:

Original iPhone    Standard SIM card

iPhone 3G               Standard SIM card

iPhone 3GS             Standard SIM card

iPhone 4 (GSM)    Micro SIM card

iPhone 4S               Micro SIM card

iPhone 5                  Nano SIM card

iPhone 5c                Nano SIM card

iPhone 5s                Nano SIM card

iPhone 6                  Nano SIM card

iPhone 6 Plus         Nano SIM card

iPhone 6s                Nano SIM card

iPhone 6s Plus       Nano SIM card

iPhone SE                Nano SIM card

iPhone 7                   Nano SIM card

iPhone 7 Plus          Nano SIM card

You can see the difference in sizes so be sure to get the right one.