Used battery for my 3-year-old MacBook Pro Retina
My MacBook Pro Retina didn't last more than 2hrs with the battery and it turned off with no warning at 25%, so I had to change it.
The repair was quicker that i expected it to be. In about 1 hour, I changed everything and my Mac was running again.
Buy the "brand new" not the used one, first because the "glue" in the used is not too strong as the original and i don't know if it's my mac or the battery it only last about 5hrs but it's better to have this that have less than 2hrs, and with this battery the mac turns off how it have to do, making sending me warning at 10% and then turn off smoothly.