The replacement battery was needed because the original battery lasted almost 2 hours, the Lenovo R61 so to speak had to be clamped to the network constantly. The purchased battery machtŽs fun again fits, wobbles and has air! The battery protrudes slightly behind, is not bad at all, finally makes it in the notebook, which is not among the thinnest anyway, hardly anything out. Performance (almost) endless, Here the price-performance ratio. Manufacturer of battery cells is Sanyo, which is a brand product. As already mentioned: top notch!