512MB KIT (2 x 256MB) For IBM-Lenovo Thinkpad Notebook Series 600X (2645-3xx) 600X (2645-4xx) 600X (2645-5xx) 600X (2645-6xx) 600X (2645-7xx) 600X (2645-8xx) 600X (2645-9xx) A20M (2628-xxx) A20M (2629-xxx) A20M (2633-xxx) A20P (2628-xxx) A20P (2629-xxx) A21E (2632-xxx) PIII A21E (2655-2xx) A21E (2655-4xx) A21E (2655-7xx) A21E (2655-9xx) A21M (2628-xxx) A21P (2629-xxx) A22M (2628-xxx) A22M (2629-xxx). SO-DIMM SD NON-ECC PC133 133MHz RAM Memory. Genuine A-Tech Brand. 512MB KIT (2 x 256MB) SO-DIMM SD NON-ECC PC133 133MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For IBM-Lenovo Thinkpad Notebook Series. (See Compatibility List Below)