Arch Memory 4 GB (1 x 4 GB) 240-Pin DDR3 UDIMM DDR3-1066 PC3-8500 RAM Arch Memory is a Registered Trademark of Arch Computer, LLC 4GB DDR3-1066 PC3-8500 240Pin Desktop UDIMM 1.5 volts Dual Rank (2Rx8) CL7 Lifetime Replacement Warranty