32GB 2 x 16GB DDR4 SO-DIMM DDR4 2400 PC4-19200 Apple iMac w/Retina 4K display ( 21.5 -inch Mid 2017), iMac ( 21.5 -inch Mid 2017) iMac18, 1 iMac18, 2 NEMIX RAM memory upgrades meet and exceed Apple and Intel specifications and are backed by Lifetime Warranty.