4GB kit (2GBx2) Upgrade for a Apple MacBook 2.1GHz Intel Core 2 Duo (13-inch White) System (DDR2 PC2-5300, NON-ECC, ) 200-pin SODIMM DDR2-667 DDR2 PC2-5300 Unbuffered, NON-ECC, DDR2-667, 1.8V, 256Meg x 64 The only brand of memory upgrade available directly from a DRAM manufacturer, tested to meet the most stringent industry specifications Install it yourself in about 15 minutes. The same top-quality memory that the worlds largest computer manufacturers install in the systems they sell