OWC 64GB (4 x 16GB) PC12800 DDR3 1600MHz SO-DIMMs Memory Compatible with 2015 (Late) iMac 27" w/Retina 5K Models and Compatible PCs (OWC1600DDR3S64S) at Amazon.com
OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
memory 1600 mhz ddr3 mac | Newegg.com
A-Tech 16GB Kit (4x4GB) RAM for Apple iMac (Late 2012, Late 2013, Late 2014, Mid 2015) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
OWC 16GB PC12800 DDR3 1600MHz SO-DIMM Memory Compatible with 2015 (Late) iMac 27" w/Retina 5K Models and Compatible PCs (OWC1600DDR3S16G) at Amazon.com