New 21.5-inch iMac least repairable yet due to lack of RAM, hard drive upgradability - 9to5Mac
Timetec Kit de 32GB (2x16GB) Compatible para Apple 2017 iMac (27 Pulgadas con Retina 5K, 21.5 Pulgadas) DDR4 2400MHz PC4-19200 SODIMM Mac RAM Upgrade para iMac18.1/iMac18.2/iMac18,3 : Amazon.es: Informática
iMac(Retina 4K,21.5-inch, Late 2015) - elalmadelgenio.com
Reemplazo de RAM del iMac Intel 21.5" Retina 4K Display (2017) - Guía de reparación iFixit
iMac Intel 21.5" EMC 2889 Teardown - iFixit
A-Tech 16GB (2x8GB) RAM for Apple iMac Late 2015 27 inch Retina 5K | DDR3L 1866MHz / 1867MHz PC3L-14900 1.35V 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
iMac RAM Upgrade 8GB-32GB (Late 2015) - YouTube
Reemplazo de RAM del iMac Intel 21.5" Retina 4K Display (2017) - Guía de reparación iFixit
Differences Between Late 2015 iMac Retina 4K/5K Models: EveryMac.com
Apple iMac 21,5" A1418 finales de 2015 Retina 4K 3,1 GHz i5 8 GB placa lógica 820-00431-A | eBay
Apple iMac 2015 (mid) 21.5-inch SSD & macOS X Upgrades - ZD Laptop Service Centre
Install memory in an iMac - Apple Support
Apple iMac with 4K Retina display (21.5-inch, 2015) review: Apple packs more pixels into its smallest iMac - CNET