RAM & Memory Upgrades
16GB (2 x 8GB) DDR3 1866MHz PC3-14900 204-PIN SODIMM MEMORY RAM COMPATIBLE WITH INTEL IMAC 27" RETINA 5K (LATE 2015)
SIZE/CAPACITY: 16GB KIT (2 x 8GB) VOLTAGE/POWER CONSUMPTION: 1.35v CAS LATENCY: CL13 SPEED: PC3-14900 (1866MHz) TYPE/INTERFACE: 204-PIN DDR3 SODIMM 204-PIN INTEL IMAC & INTEL MAC MINI DDR3 SODIMM
https://www.bizrate.co.uk/ram_memoryupgrades/16gb-2-x-8gb-ddr3-oid6623015804.html