This product is a set of four 1MB SIMM memory modules with a total capacity of 4MB, designed for vintage computers. The modules have a 30-pin design and a bus speed of 10ns. Manufactured by Hitachi in the United States, these FPM Parity modules are compatible with various brands such as Sun, IBM, Compaq, and HP. Perfect for restoring or upgrading old computer systems, these memory modules offer a reliable and high-quality solution for increasing storage capacity.