IBM BladeCenter JS21 (Type 8844), JS22 (Type 7998), LS21 (Type 7971), LS22 (Type 7901) compatible Black Diamond memory 4GB 2X2GB DDR2 ECC Registered RDIMM 667MHz. Compatible computer model: IBM BladeCenter JS22 (Type 7998), LS22 (Type 7901), HS20 (Type 1883), LS42 (Type 7902), LS21 (Type 7971), HS12 (Type 8014 and 8028), HS20 (Type 8843), HS20 (Type 7981), JS12 (Type 7988), JS21 (Type 8844), LS41 (Type 7972), JS21 (Type 7988). Black Diamond Memory offers the most extensive line of memory solutions today. With our decades of experience specializing in memory, Black Diamond Memory is a proven manufacturer to the semiconductor industry. Our great products combined with our world class service and support have helped us to where we are today. When you have an Black Diamond memory chip, you can count on it being the best available memory for your system. Our system specific Branded Memory line delivers in performance, and is designed to be guaranteed in compatibility with your system. Each of our memory chips come with a lifetime warranty for your peace of mind. Use our Upgrade Configurator to easily find the correct memory module for your system. Please keep in mind that this memory will ONLY work on the models listed above. 15% Restocking fee will apply for non-defective items.