Used, works great.  The Samsung 4GB PC4-21300 DDR4 2666 MHz SODIMM Laptop Memory RAM is a high-quality memory module designed for laptops, notebooks, and all-in-ones. With a total capacity of 4GB and a frequency of 2666MHz, this DDR4 SDRAM RAM provides fast and reliable performance. The memory features non-ECC unbuffered technology and has a lifetime manufacturer warranty, ensuring long-lasting durability. This single module memory is a great choice for upgrading or replacing existing memory modules in laptops and notebooks for improved efficiency and speed.