Excellent guide that was easy to follow and left no unwanted surprises. Never opened a MacBook air (A1466) before so all new to me and had no trouble at all. I bought a new Hasess A1405 battery (https://www.amazon.co.uk/gp/product/B016...) which came with the necessary screwdrivers that worked fine. They were magnetised, as mentioned by another commenter, which was really handy as the screws are very small. The battery was sold as a 6800mAh/50Wh but the system information (Power) was showing it as 7188mAh which was a very pleasant surprise. Mine is a mid 2012 MBA and has the plastic tab on the old battery (and new battery) so pulling out horizontally, not vertically, worked like a treat. Interestingly, in response to comments about battery holes not lining up or breaking, my apple battery had broken 2 clips which left bits of plastic in the case that I needed to pick out before fitting the new battery. It didn't cause a problem to the operation of my MBA. Thanks!