Infineon top quality memory module HYS72D32501GR-7-A 32Mx72 DDR SDRAM 266MHz IBM label 11838L4029Z1JMXA8BX06G FRU:09N4306 256MB 32Mx72 2.5V 133MHz DDR ECC OPT:33L5037 INF311 for IBM xSeries eServer One double sided registered DIMM with ECC error checking and correcting This will only fit in a machine which is keyed for REG SDRAM DIMM's, that is memory which is both ECC and registered which means most server boards and some performance workstations only (fully buffered boards are often backward compatible) Fully tested and working