A-TECH 4GB STICK For Acer Aspire 4250 4250-BZ637 5250-0450 5250-0468 5250-0639 5250-0895 5250-BZ455 5250-BZ641 5250-BZ853 5250-BZ873. SO-DIMM DDR3 NON-ECC PC3-12800 1600MHz RAM Memory. Genuine Brand. 4GB STICK SO-DIMM DDR3 NON-ECC PC3-12800 1600MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For Acer Aspire. (See Compatibility List Below)