OWC 4x16GB (64GB) 2666MHz DDR4 PC4-21300 SODIMM 260-Pin, 1.2 Volts, Non-registered, Non-ECC, Fully compliant with JEDEC specifications, ROHS compliant, warranty safe upgrade, CYCLE TIME: 0.75 ns, TIMING: CAS = 18.0, Full Parameters: 18-18-18-14, BANDWIDTH: 21.3GB/s, Low noise 8-layer PCB, OWC Memory is the most cost effective and simple DIY upgrade you can install to unleash your Mac or PC's full potential, and speed up overall responsiveness.Become a multi-tasking maven when you upgrade your Mac or PC with OWC Memory. Open more apps. Open larger files. Plus, work with multiple files all at the same time. We test every OWC memory module at our in-house lab so you can upgrade with the confidence that your memory is built-to-last. We built your OWC Memory upgrade to meet or exceed the toughest industry specs to provide years of worry-free service. Note: For 27-inch iMac (2020) models — iMac20,1 and iMac 20,2 — OWC recommends that all DIMMs be the same capacity, speed, and manufacturer to ensure optimal memory performance.