A Crucial memory upgrade is the one of the easiest & most inexpensive ways to increase system performance. CT2KIT25664BF1339 is a 4GB kit consisting of (2) 2GB DDR3 Notebook modules that operates at speeds up to 1333 MT/s & has a CL9 latency. It is dual voltage & can operate at 1.35V or 1.5V. It is Unbuffered & is non-ECC. It conforms to the industry standard SODIMM layout of 204 pins & is compatible with computers that take DDR3 SODIMM memory.