I used to have a small robot vacuum cleaner, something like a rumba in the battery, although it looked new, but was not fully charged due to its age. I bought this device which has a little more power (mAh) and still works like a charm. The overall size of the battery was almost identical to the standard battery and works with the same charger. With extended cleaning/run times and a great price, time will tell but it seems like a great investment.