To find out what model iPhone you have, just look on the back and check the model number. Compare with numbers below to find out your model. Hope this helps!
iPhone 7 Plus | 2016 | A1661/A1784
iPhone 7 | 2016 | A1660/A1778
iPhone 6S Plus | 2015 | A1687
iPhone 6S | 2015 | A1688
iPhone 6 Plus | 2014 | A1524
iPhone 6 | 2014 | A1549
iPhone 5S | 2013 | A1530
iPhone 5C | 2013 | A1529
iPhone 5 | 2012 | A1429
iPhone 4S | 2011 | A1387
iPhone 4 | 2010 | A1332
iPhone 3GS | 2009 | A1303
iPhone 3G | 2008 | A1241
iPhone | 2007 | A1203