Refurbished Lenovo ThinkCentre M81 Small Form Factor (SFF) computer powered by Intel Core i5-2400 @ 3.10 GHz (2nd generation) CPU with 4GB DDR3 RAM and 500GB HDD. This computer has NO OPERATING SYSTEM installed. The buyer is responsible for acquiring and installing their own version of Windows or other OS. This product is covered by a full 365 day Parts and Labor warranty!