4GB TOTAL 1PC OF 4GB DDR3 PC3-12800 CL=11 Unbuffered NON-ECC DDR3-1600 1.5V 1024Meg x 64, PC1333 WILL WORK AS WELL Compatible with: Aspire Acer V5-122P-0679, V5-122P-0681, V5-122P-0825 Acer part numbers NX.M8WAA.009, NX.M91AA.009, NX.M8WAA.011 Genuine CMS brand, CMS is one of the most trusted names in the Computer Memory industry and this product carries a Lifetime Warranty from CMS Maximum Memory: 10GB Expansion: 1 Socket(s)