iMac 21,5'' Late 2009iMac 21,5'' Mid 2010-Mid 2011iMac 21,5'' Late 2012-Late 2013iMac 21,5'' Mid 2014-Mid 2017 4KiMac 27'' Late 2009iMac 27'' Mid 2010-Mid 2011iMac 27'' Late 2012-Mid 2015 5KiMac 27'' Late 2015 5KiMac 27'' Mid 2017 5K