The Micron Crucial 2x2GB DDR2 ECC Server Memory Kit includes two DIMM modules with a total capacity of 4GB. The memory modules are designed for server use and feature ECC memory for error correction. With a bus speed of PC2-5300 (DDR2-667), this memory kit is ideal for enhancing the performance and reliability of servers in enterprise networking environments. The MT18HTF12872FDY-667D5D3 model ensures compatibility and quality for your server memory needs.