The IBM 256MB SDR SDRAM PC-66 DIMM 168-Pin Non-ECC Unbuffered 40H8582 is a memory module designed for use in computers. It has a total capacity of 256 MB, with each module providing 256 MB of memory. This module is specifically designed for IBM systems and features a DIMM form factor with 168 pins. The memory is non-ECC and unbuffered, making it ideal for systems that require reliable and fast memory performance. With a length of 5.25 inches, height of 3.0 inches, and width of 1.2 inches, this memory module is a dependable choice for enhancing the performance of your computer system.