8GB kit, (2 x 4GB) 240-pin DIMM, DDR3 PC3-10600U,Dual Rank, Non ECC ram Memory Module by Hynix (HMT351U6CFR8C-H9) at Amazon.com
CORSAIR Vengeance LPX - DDR4 - 16 GB: 2 x 8 GB - DIMM 288-pin - unbuffered | Dell USA
Corsair Vengeance SO-DIMM DDR4 64 GB (2 x 32 GB) 3200 MHz CL22 - PC RAM Corsair on LDLC
Integral 16GB (2x 8GB) 2400MHz DDR4 DIMM PC Memory Module Kit £45.96 - Free Delivery | MyMemory
parts-quick 8GB (2 X 4GB) Kit Memory Module for Apple iMac 27" 2017 5K Retina Display DDR4 2400MHz SO-DIMM RAM at Amazon.com
Amazon.com: OWC 32GB (2 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S32P) : Everything Else