Samsung 4GB PC3-12800 DDR3-1600MHz non-ECC Unbuffered CL11 240-Pin DIMM Dual Rank Memory Module (M378B5273CH0-CK0 655410-150). This is a seller refurbished part in great working condition. May show signs of cosmetic wear but this should not interfere with the effectiveness of the product. Taken from a working environment.