Amazon.com: OWC 8GB (2 x 4GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S08P) : Everything Else
Arch Memory 4GB 204-Pin DDR3 1333 MHz So-dimm RAM for Lenovo ThinkPad T520 4239-4MU at Amazon.com