CT51264BF1339 is a single 4gb ddr3 notebook module that operates at speeds up to 1333 mt/s and has a cl9 latency. It is dual voltage and can operate at 1.35v or 1.5v. It is unbuffered and is non-ECC. It conforms to the industry standard SODIMM layout of 204 pins and is compatible with computers that take ddr3 SODIMM memory.