Good product, although the brand of these cells are not known (Unix Dell Announces cells, but Dell is not a cell manufacturer ...) Cells of major brands (Sanyo etc ... as in batteries Original Dell) bring greater autonomy and above all reliability. Autonomy is correct (about 3:30 to 4:00) achieved battery life with Dell original battery capacity for a lower advertised ... So can do better, but we will see the life. great price value.