OWC 16GB (2 x 8GB) 1867 MHZ DDR3 SO-DIMM PC3-14900 204 Pin CL11 Memory Upgrade, (OWC1867DDR3S16P) 16.0 GB (2 x 8GB) 1867 MHZ DDR3 SO-DIMM PC3-14900 204 Pin CL11 Memory Upgrade Memory upgrade kit For 2015 (Late) iMac 27" w/ Retina 5K models (October 2015) Model ID:iMac17,1: 3.2GHz i5, 3.3GHz i5, 4.0GHz i7 OWC Memory Lifetime Limited Warranty including the OWC Lifetime Advanced Replacement Program Product Specs: Technology:DDR3 SO-DIMM RoHS:Yes Pin Count:204-pin Op. Data Rate:DDR3-1867 Speed:PC3-14900 CL:11 Cycle Time:1.875ns Voltage:1.35V ECC:Non ECC Module Ranks:Dual Rank Register:Non Parity. Low Noise 8-Layer PCB Meets and/or Exceeds Apple/Intel Specifications. Fully Compliant with JEDEC specification. RoHS Certified