The accuracy of fit is not quite as outstanding as reported in my copies of the other reviewers: voluntarily leave the batteries the computer not only with the support of a small screwdriver you get out of there. However, they close fairly smoothly from the computer back, ie without 1mm supernatant as with other types.
However, the capacity I was a bit disappointed: the latest after just 1.5 hours on medium screen brightness and light load is closing, the movies look after about an hour. The data on capacity are therefore "somewhat" optimistic advertised the battery with 5500 mAh, on the packaging is even 5600 mAh. The System Profiler and various battery monitor programs report a design capacity of 5200 mAh. The one with the Mini Battery Logger aufgezeichte average power consumption (less than 2 A during a period of 1.3 hours), however, suggests an actual capacity of 2550 mAh whole, ie less than half the advertised value. Since both batteries have a nearly identical capacity, should not be due to manufacturing tolerances. Since the energy stored in battery design capacity (which is used by the operating system for forecasting the remaining term, and will therefore always given far too long) is far higher than the actual capacity, you can probably assume bad faith by the manufacturer.
Nevertheless, the price of 2 of these batteries (which together reach nearly the capacity of a genuine 5500 mAh batteries) still only one third of Apple's price, so the price / performance ratio is very good even taking into account the actual capacity. However annoying the terminals when removing the battery from the computer, because you have to do the traveling quite often because of the low range.