Crucial 4GB (1x 4GB) DDR4 2666MHz Single-Rank So-DIMM Memory - DDR4 PC4-21300 - CL=19 - Single Ranked - x8 based - Unbuffered - NON-ECC - DDR4-2666 - 1.2V - 512Meg x 64 - CT4G4SFS8266 - Limited Product Lifetime Warranty 4GB DDR4 2666 MT/s (PC4-21300) CL19 SR x8 SODIMM 260pin