The Samsung 4GB 1Rx8 PC3-12800U-11-13-A1 NON-ECC Unbuffered Memory is a high-quality memory module designed for computers. With a total capacity of 4GB and a bus speed of PC3-12800U, it provides fast and reliable performance for any system. As a DDR3 SDRAM module in UDIMM form factor, it is unbuffered and non-ECC, making it ideal for various computing tasks. With the trusted Samsung brand and specific model number M378B5173QH0-CK0, this memory module is a great choice for upgrading or replacing existing memory modules in your computer system. All are used and pulled from working desktops.