The 647895-B21 is a DDR3 memory module produced by HP, known for its reliability and performance in server environments. This module falls within the DDR3 1600 SODIMM category, with a configuration of 512Mx72 ECC Registered/ RDIMM, emphasizing its use in servers and workstations where error correction and data integrity are crucial. The module operates at a standard speed of 1600 MHz, ensuring compatibility with a broad array of enterprise-level hardware that supports DDR3 memory at this clock rate. This particular model has a capacity of 4GB, arranged in a 1Rx4 configuration, meaning it has a single rank of memory with data paths organized in four banks, optimized for efficient data retrieval and storage. The presence of ECC (Error Correcting Code) is a key feature, reducing the risk of data corruption and system crashes by automatically correcting data errors in real-time, a vital necessity in mission-critical server applications. The module's RDIMM (Registered DIMM) design also makes it suitable for systems demanding high stability and scalability, as it contains a register that delays data and commands for one clock cycle, ensuring better stability in environments running large amounts of memory.