The purchase is for one 8MB flash memory SIMM made of AMD chips. It is requires updated boot rom version (Boot-2500) with separated purchase. It is compatible with the following router: 2501, 2502, 2503, 2504, 2505, 2507, 2509, 2510, 2511, 2512, 2513, 2514, 2515, 2516, 2517, 2518, 2519, 2520, 2521, 2522, 2523, 2524, 2525.