Hynix/Lenovo 4GB PC3-12800 DDR3-1600MHz non-ECC Unbuffered CL11 204-Pin SoDimm Single Rank Memory Module (HMT451S6MFR8C-PB 03X6561). 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.