Apple makes it hard sometimes as they change the method they use to distinguish the different models. IFIXIT focus on common design one or more systems are based on. As of late Apple has been focusing on a common design with the 'Thin iMac's'
Here's the guides for your system: iMac Intel 21.5" Retina 4K Display 2015 Repair
"A1418 / EMC 2833 / Late 2015 / 3.1 GHz Core i5 or 3.3GHz Core i7 Processor. Released October 13, 2015."
What are you trying to do?
crwdns2934105:0crwdne2934105:0
crwdns2934113:0crwdne2934113:0
crwdns2915270:0crwdne2915270:0
crwdns2889612:0crwdne2889612:0
1