The IBM 4GB ECC Registered DIMM Dual Rank Memory Module is a reliable and stable option for users who require a high level of reliability in their systems. This module has a capacity of 4GB and is designed for use in server environments. It has an ECC (Error Correcting Code) feature that helps to detect and correct errors in data transmission, ensuring the integrity of the data being processed. This module also has a dual rank design, which allows it to have a higher data transfer rate than single rank modules. The IBM 4GB ECC Registered DIMM Dual Rank Memory Module is a great choice for users who require a stable and reliable memory module for their server environments.