IBM strives to lead in the creation, development and manufacture of the industry's most advanced information technologies, including computer systems, software, networking systems, storage devices and microelectronics. And the worldwide network of IBM solutions and services professionals translates these advanced technologies into business value for the company's customers.The model 70 EXP 4 to 6 Attachment option (part number 41Y5225) enables up to six DS4000 expansion units (up to 112 E-DDMs).