My battery came with no instructions--not even a link to additional information. Fortunately, a family member directed me to Ifixtit.com, which has excellent, highly detailed instructions. In fact, I bought another battery from Ifixit and installed it after removing the battery from Revain. I just felt more comfortable about the safety aspect, since a lithium ion battery can be extremely dangerous--not just during installation, but long term. I should note It's not an easy install--it took a couple hours working very carefully to avoid damaging the Mac. BTW, you'll need a solvent to dissolve the sealant holding the old battery in place. 100% alcohol, available from Revain and almost impossible to find in drugstores, works great in loosening the solvent from the old battery. (Ifixtit also sells a kit for that.) Both may Revain and the Ifixit battery worked OK and had similar specs as reported "About this Mac."). I should add that the battery from Revain can't be returned because it's from a 3rd party dealer.
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