I had an alarm of Service Battery for my laptop (Battery Cycle 79), tried a lot to calibrate it as Apple recommendations but useless.
So i tried to find the battery locally in my city but it was not available and it will take 1 month to order from dealer and 4 days for installation, because the queue is so long.
I made the order from iFixit, and receive it within 3 days and the surprise that it was a Genuine Apple Battery and a brand new one.
It took me only 20 min to install it and now i can travel without any fear to runout of power.
If you want to do this kind of replacements by your own, you should have the Pro Kit because it is suitable for all kind of electronics and read the guide carefully.