These high quality 1GB DDR2 Memory modules from Buffalo Technology, the number one memory module manufacturer in Japan, are an ideal choice for building your own system, or upgrading/replacing your existing memory. They are built to Buffalo's high manufacturing standards, so they are cost effective without sacrificing quality. These modules have been 100% tested with all major motherboards for optimal compatibility. They are backwards compatible, so they will work with motherboards that use DDR2 PC 3200/400MHz and DDR2 PC 4200/533MHz, as well as DDR2 PC 5300/667MHz. The modules are covered by a Lifetime Warranty.