The ProMOS 512MB X2 1GB Memory Ram is a set of two DDR2 SDRAM modules designed for desktop computers. Each module has a capacity of 512 MB, providing a total combined capacity of 512GB. The memory modules have a form factor of DIMM and a bus speed of PC2-5300 (DDR2-667), making them compatible with systems that require this specific type of RAM. With the brand being ProMOS Technologies, you can trust in the quality and reliability of the product for improving the performance of your computer.