I installed this battery pretty easily on a compatible MacBook Pro (Mid 2012) and it was great for the first week or so. After that, the MacBook was incredibly unstable and would not stay running (even connected to power) for more than an hour before crashing. I did a bunch of troubleshooting thinking my older Mac was starting to show it's age in other ways, but to no avail. As a last hail Mary effort, I ended up putting the battery I replaced back in to the machine and it has been stable since. I am unable to return this battery at this point, but I definitely would if I could. Pretty much a waste of time and money.
Crashed Macbook so many times