I bought this to replace an ailing original battery for my 20 month old Samsung R519. It came with instructions for battery care (in pigeon English but understandable) and was already partially charged. It slotted in perfectly and my battery life is now back to 2 1/2 to 3 hrs like the Samsung battery was when new! The only negative is the battery meter in Windows 7 is constantly giving different estimates of the time left in the battery - but I just ignore that and go by the % of battery charge left which is more accurate.
By the way it was cheaper on here than on Amazon and from the same seller!