Memory in iMac (21.5-inch, Late 2015), and iMac (Retina 4K, 21.5-inch, Late 2015) is not upgradeable. Before you schedule an appointment, confirm that the specific Apple Authorized Service Provider offers memory upgrade services. If you’d like to upgrade the memory in one of these models, an Apple Authorized Service Provider can help. If the memory in one of these computers needs repair service, contact an Apple Retail Store or Apple Authorized Service Provider. If you're not sure which iMac you have, you can identify your iMac and then select it from the list below. The line that reads ‘Memory’ will tell you if your Mac has the necessary 2GB of RAM or if you will need to upgrade before you can install OS Yosemite.
Visit the Apple site to learn, buy, and get support. Check out MacBook Pro, iMac Pro, MacBook Air, iMac, and more. Crucial Memory and SSD upgrades - 100% Compatibility Guaranteed for apple - FREE US Delivery Crucial Memory and SSD upgrades - 100% Compatibility Guaranteed for apple - FREE US Delivery.