The CT12864Z40B by Crucial is a DDR 400 memory module, offering compatibility with systems supporting 184-pin DDR (PC3200) memory. With a 128Mx64 data configuration, it provides 1GB of RAM, making it an excellent choice for users looking to upgrade their desktop computer's memory capacity. This module's DDR-400 classification means it operates at 400MHz, allowing for quicker data access and improved system performance. Ideal for various computing activities, from daily tasks to more memory-demanding applications, the CT12864Z40B helps to ensure that systems operate more fluidly and reliably. As a product of Crucial, a brand well-regarded for its quality and reliability in memory technologies, users can trust in its performance and durability.